Tüm alıştırma soruları

2131 soru

Soru 2081Soru

Let xx and yy be non-zero integers such that x5y2<0x^5 y^2 < 0 and x+yx + y is an odd integer. Which of the following statements MUST be true? Select all that apply.

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Cevap: xx is a negative integer; xyxy is an even integer; x2+y2x^2 + y^2 is an odd integer

Cevap

The statements 'xx is a negative integer', 'xyxy is an even integer', and 'x2+y2x^2 + y^2 is an odd integer' MUST be true.
The statement specifying that 'xx is a negative integer' is true because y2y^2 is strictly positive for any non-zero integer yy, forcing x5<0x^5 < 0 and thus x<0x < 0. The statement 'xyxy is an even integer' is true because x+yx + y being odd requires one variable to be even and the other to be odd, making their product even. The statement 'x2+y2x^2 + y^2 is an odd integer' is true because the square of an even number is even and the square of an odd number is odd, and their sum is always odd.

Adım Adım Çözüm

1
Determine the sign of xx from the given inequality x5y2<0x^5 y^2 < 0.
xx must be negative (x<0x < 0).
Since yy is a non-zero integer, y2>0y^2 > 0. Dividing the inequality by y2y^2 gives x5<0x^5 < 0, which means xx must be negative.
2
Analyze the parity (even/odd nature) of xx and yy using x+yx + y is odd.
One of x,yx, y is even and the other is odd.
The sum of two integers is odd if and only if one integer is even and the other is odd.
3
Evaluate the statement 'xyxy is an even integer'.
The product xyxy is always even.
The product of an even integer and an odd integer is always even.
4
Evaluate the statement 'x2+y2x^2 + y^2 is an odd integer'.
The sum of squares x2+y2x^2 + y^2 is always odd.
Squaring an even integer yields an even integer, and squaring an odd integer yields an odd integer. Adding an even number and an odd number yields an odd number.

Anahtar Kavram

Even-Odd Parity Rules and Exponent Sign Properties
Soru 2082Soru

An agricultural facility uses three conveyor belts—XX, YY, and ZZ—to transfer harvested grain into a storage silo. Working together at their respective constant rates, Belt XX and Belt YY can fill the empty silo in 6 hours6\text{ hours}. Working together at their respective constant rates, Belt YY and Belt ZZ can fill the empty silo in 8 hours8\text{ hours}. If Belt XX operates at twice the rate of Belt ZZ, how many hours would it take Belt YY working alone at its constant rate to fill the empty silo?

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Cevap: 12 hours12\text{ hours}

Cevap

12 hours12\text{ hours}
The correct answer is 12 hours12\text{ hours}. Subtracting the combined rate equation for Belts YY and ZZ (rY+rZ=1/8r_Y + r_Z = 1/8) from the equation for Belts XX and YY (rX+rY=1/6r_X + r_Y = 1/6) yields rXrZ=1/24r_X - r_Z = 1/24. Since Belt XX works at twice the rate of Belt ZZ (rX=2rZr_X = 2r_Z), substituting gives rZ=1/24r_Z = 1/24. Substituting rZr_Z back into rY+rZ=1/8r_Y + r_Z = 1/8 gives rY=1/81/24=1/12r_Y = 1/8 - 1/24 = 1/12. Therefore, Belt YY operating alone takes 12 hours12\text{ hours} to fill the silo.

Adım Adım Çözüm

1
Define the work rates of each conveyor belt.
Let rXr_X, rYr_Y, and rZr_Z be the fraction of the silo filled per hour by Belts XX, YY, and ZZ, respectively.
Establishing rates per unit of time allows linear combination of work performed.
2
Set up equations based on the given combined times and rate relationships.
rX+rY=16r_X + r_Y = \frac{1}{6}, rY+rZ=18r_Y + r_Z = \frac{1}{8}, and rX=2rZr_X = 2r_Z.
Combined rates equal the reciprocal of the total time required for combined work.
3
Subtract the second equation from the first to isolate rXrZr_X - r_Z.
(rX+rY)(rY+rZ)=1618    rXrZ=4324=124(r_X + r_Y) - (r_Y + r_Z) = \frac{1}{6} - \frac{1}{8} \implies r_X - r_Z = \frac{4 - 3}{24} = \frac{1}{24}.
Eliminating rYr_Y gives a direct linear relationship between rXr_X and rZr_Z.
4
Substitute rX=2rZr_X = 2r_Z into rXrZ=124r_X - r_Z = \frac{1}{24} to solve for rZr_Z.
2rZrZ=124    rZ=1242r_Z - r_Z = \frac{1}{24} \implies r_Z = \frac{1}{24}.
Determines the individual rate of Belt ZZ.
5
Substitute rZ=124r_Z = \frac{1}{24} back into the equation rY+rZ=18r_Y + r_Z = \frac{1}{8} to find rYr_Y.
rY=18124=324124=224=112r_Y = \frac{1}{8} - \frac{1}{24} = \frac{3}{24} - \frac{1}{24} = \frac{2}{24} = \frac{1}{12}.
Finds the individual rate of Belt YY.
6
Calculate the time required for Belt YY alone.
\text{Time} = \frac{1}{r_Y} = 12\text{ hours}.
The time to complete one full job is the reciprocal of the individual rate.

Anahtar Kavram

Work Rates and Combined Rate Equations
Soru 2083Soru

A quadratic function is defined by f(x)=ax2+bx+cf(x) = ax^2 + bx + c, where aa, bb, and cc are real constants with a>0a > 0. If the vertex of the parabola y=f(x)y = f(x) lies in the third quadrant of the xyxy-plane, which of the following statements must be true? Select all that apply.

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Cevap: b>0b > 0; The equation f(x)=0f(x) = 0 has two distinct real solutions.

Cevap

The statements 'b>0b > 0' and 'The equation f(x)=0f(x) = 0 has two distinct real solutions' must be true.
The vertex of the parabola y=ax2+bx+cy = ax^2 + bx + c is (h,k)=(b2a,cb24a)(h, k) = \left(-\frac{b}{2a}, c - \frac{b^2}{4a}\right). Because the vertex is in the third quadrant, h<0h < 0 and k<0k < 0. With a>0a > 0, the inequality b2a<0-\frac{b}{2a} < 0 directly requires b>0b > 0. Furthermore, because a>0a > 0 (parabola opens upward) and the minimum value k<0k < 0 lies below the x-axis, the graph must cross the x-axis at two distinct points, establishing that f(x)=0f(x) = 0 has two distinct real solutions.

Adım Adım Çözüm

1
Analyze the coordinates of the vertex (h,k)(h, k) relative to the third quadrant.
The third quadrant requires h<0h < 0 and k<0k < 0.
Points in Quadrant III have negative x-coordinates and negative y-coordinates.
2
Evaluate the sign of bb using the x-coordinate formula h=b2ah = -\frac{b}{2a}.
b>0b > 0.
Since h<0h < 0 and a>0a > 0, b2a<0    b2a>0    b>0-\frac{b}{2a} < 0 \implies \frac{b}{2a} > 0 \implies b > 0.
3
Determine the number of real solutions using the vertex y-coordinate kk and orientation a>0a > 0.
The discriminant b24ac>0b^2 - 4ac > 0, giving two distinct real solutions.
For an upward-opening parabola (a>0a > 0), having a vertex below the x-axis (k<0k < 0) guarantees the curve crosses the x-axis twice.
4
Test counterexamples for cc and evaluate the root sum ba-\frac{b}{a}.
cc is not strictly constrained in sign, and the root sum is negative.
The function f(x)=(x+2)21=x2+4x+3f(x) = (x+2)^2 - 1 = x^2 + 4x + 3 has vertex (2,1)QIII(-2, -1) \in \text{QIII} with c=3>0c = 3 > 0. Also, since a>0a > 0 and b>0b > 0, root sum ba<0-\frac{b}{a} < 0.

Anahtar Kavram

Parabola Vertex and Quadratic Discriminant Analysis
Soru 2084Soru
For all real numbers xx and yy such that xyx \neq y, xyx \neq -y, and x2+y20x^2 + y^2 \neq 0, which of the following expressions is equivalent to
x4y4x3x2y+xy2y32xyx+y\frac{x^4 - y^4}{x^3 - x^2 y + x y^2 - y^3} - \frac{2 x y}{x + y}
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Cevap: x2+y2x+y\frac{x^2 + y^2}{x + y}

Cevap

x2+y2x+y\frac{x^2 + y^2}{x + y}
Factoring x4y4x^4 - y^4 as (xy)(x+y)(x2+y2)(x - y)(x + y)(x^2 + y^2) and x3x2y+xy2y3x^3 - x^2 y + x y^2 - y^3 as (xy)(x2+y2)(x - y)(x^2 + y^2) simplifies the first term to x+yx + y. Combining x+yx + y with 2xyx+y-\frac{2xy}{x+y} over the common denominator (x+y)(x + y) gives (x+y)22xyx+y=x2+y2x+y\frac{(x+y)^2 - 2xy}{x+y} = \frac{x^2 + y^2}{x+y}.

Adım Adım Çözüm

1
Factor the numerator and denominator of the first rational expression
Numerator: x4y4=(x2y2)(x2+y2)=(xy)(x+y)(x2+y2)x^4 - y^4 = (x^2 - y^2)(x^2 + y^2) = (x - y)(x + y)(x^2 + y^2). Denominator: x3x2y+xy2y3=x2(xy)+y2(xy)=(xy)(x2+y2)x^3 - x^2 y + x y^2 - y^3 = x^2(x - y) + y^2(x - y) = (x - y)(x^2 + y^2).
Factoring allows for cancellation of common factors in rational expressions.
2
Simplify the first rational expression by canceling common terms
(xy)(x+y)(x2+y2)(xy)(x2+y2)=x+y\frac{(x - y)(x + y)(x^2 + y^2)}{(x - y)(x^2 + y^2)} = x + y.
Since xyx \neq y and x2+y20x^2 + y^2 \neq 0, the common terms (xy)(x - y) and (x2+y2)(x^2 + y^2) are non-zero and can be divided out.
3
Subtract the second expression using a common denominator
(x+y)2xyx+y=(x+y)2x+y2xyx+y=(x+y)22xyx+y(x + y) - \frac{2xy}{x + y} = \frac{(x + y)^2}{x + y} - \frac{2xy}{x + y} = \frac{(x + y)^2 - 2xy}{x + y}.
Combining terms under the common denominator (x+y)(x + y) enables algebraic reduction.
4
Expand the squared binomial in the numerator and simplify like terms
\frac{x^2 + 2xy + y^2 - 2xy}{x + y} = \frac{x^2 + y^2}{x + y}.
Expanding (x+y)2=x2+2xy+y2(x + y)^2 = x^2 + 2xy + y^2 allows the +2xy+2xy and 2xy-2xy terms to cancel out.

Anahtar Kavram

Simplifying rational expressions using polynomial factoring (difference of squares and grouping) and common denominators.
Tahmini Süre:2m 0s
Soru 2085Soru

A sequence of 40 numbers a1,a2,,a40a_1, a_2, \dots, a_{40} is defined by the formula ak=15+3k8a_k = 15 + \frac{3k}{8} for each integer kk from 1 to 40. Each term aka_k is rounded to the nearest integer to form a new sequence b1,b2,,b40b_1, b_2, \dots, b_{40}. (Note: numbers ending in .5.5 are rounded up to the next integer.) What is the value of k=140bkk=140ak\sum_{k=1}^{40} b_k - \sum_{k=1}^{40} a_k?

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Cevap: 2.52.5

Cevap

The sum of the rounded sequence exceeds the sum of the exact sequence by 2.52.5.
Evaluating ak=15+3k8a_k = 15 + \frac{3k}{8} for k=1,2,,8k = 1, 2, \dots, 8 yields fractional parts of 0.375,0.75,0.125,0.5,0.875,0.25,0.625,0.375, 0.75, 0.125, 0.5, 0.875, 0.25, 0.625, and 0.00.0. The individual rounding errors (bkak)(b_k - a_k) for these terms are 0.375,+0.25,0.125,+0.5,+0.125,0.25,+0.375,-0.375, +0.25, -0.125, +0.5, +0.125, -0.25, +0.375, and 0.00.0. Summing these errors yields +0.5+0.5 per 8-term period. For 40 terms (5 full periods), the total error sum is 5×0.5=2.55 \times 0.5 = 2.5.

Adım Adım Çözüm

1
Analyze the fractional part of ak=15+3k8a_k = 15 + \frac{3k}{8} over one complete 8-term period.
The fractional parts for k=1,2,,8k = 1, 2, \dots, 8 are 0.375,0.75,0.125,0.5,0.875,0.25,0.625,0.00.375, 0.75, 0.125, 0.5, 0.875, 0.25, 0.625, 0.0 respectively.
Since 3k8\frac{3k}{8} repeats its fractional pattern modulo 8, examining one period reveals the periodic rounding behavior.
2
Calculate the rounding error (bkak)(b_k - a_k) for each term in the 8-term cycle.
The differences (bkak)(b_k - a_k) for k=1k=1 to 88 are: 0.375,+0.25,0.125,+0.5,+0.125,0.25,+0.375,0.0-0.375, +0.25, -0.125, +0.5, +0.125, -0.25, +0.375, 0.0.
Rounding to the nearest integer shifts each number by its distance to that integer. Half-integers like 0.50.5 round up, yielding a +0.5+0.5 difference.
3
Sum the rounding errors over one 8-term cycle.
(0.375+0.375)+(0.250.25)+(0.125+0.125)+0.5+0.0=+0.5(-0.375 + 0.375) + (0.25 - 0.25) + (-0.125 + 0.125) + 0.5 + 0.0 = +0.5.
Symmetric fractional pairs cancel out, leaving only the +0.5+0.5 error from the half-integer term.
4
Multiply the single-cycle error sum by the number of full cycles in 40 terms.
Since 40=5×840 = 5 \times 8, total difference =5×0.5=2.5= 5 \times 0.5 = 2.5.
The 40 terms consist of 5 identical 8-term periodic cycles.

Anahtar Kavram

Periodic error analysis in sequence rounding and summation
Soru 2086Soru

A civil engineering laboratory prepares a composite soil mixture using three material grades: Grade XX, Grade YY, and Grade ZZ. Initially, the ratio of Grade XX to Grade YY by weight is 1:21 : 2, and the ratio of Grade YY to Grade ZZ by weight is 3:43 : 4. A technician adds 30 kg30\text{ kg} of Grade XX to the batch, causing Grade XX to constitute exactly 14\frac{1}{4} of the total weight of the new mixture. Which of the following statements about the batch must be true? Select all such statements.

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Cevap: The initial total weight of the mixture before Grade XX was added was 306 kg306\text{ kg}.; The weight of Grade ZZ in the mixture is 144 kg144\text{ kg}.; In the final mixture, the ratio of Grade YY to Grade ZZ by weight is 3:43 : 4.

Cevap

The correct statements are those indicating that the initial total weight of the mixture was 306 kg, the weight of Grade Z in the mixture is 144 kg, and the ratio of Grade Y to Grade Z in the final mixture is 3 : 4.
The unified ratio of X : Y : Z is 3 : 6 : 8. Setting up the fraction of Grade X after adding 30 kg gives (3k + 30) / (17k + 30) = 1/4, which yields k = 18. This gives an initial total weight of 17 * 18 = 306 kg, a Grade Z weight of 8 * 18 = 144 kg, and an unchanged Grade Y to Grade Z ratio of 108 : 144 = 3 : 4. Therefore, the statements asserting the initial total weight as 306 kg, the Grade Z weight as 144 kg, and the final Y to Z ratio as 3 : 4 are all correct.

Adım Adım Çözüm

1
Unify the two given ratio relationships into a single 3-part ratio.
Grade X : Grade Y = 1 : 2 = 3 : 6, and Grade Y : Grade Z = 3 : 4 = 6 : 8. Unified ratio Grade X : Grade Y : Grade Z = 3 : 6 : 8.
Matching the term for Grade Y across both ratios enables setting up unified algebraic variable parts.
2
Define initial quantities using a common multiplier k.
Initial weight of X = 3k, Y = 6k, Z = 8k. Initial total weight = 3k + 6k + 8k = 17k.
Expressing quantities in terms of k allows setting up an equation after adding material.
3
Formulate and solve the equation based on the addition of Grade X.
(3k + 30) / (17k + 30) = 1/4 => 4(3k + 30) = 17k + 30 => 12k + 120 = 17k + 30 => 5k = 90 => k = 18.
Setting the new weight of X over the new total weight equal to 1/4 determines the exact value of k.
4
Evaluate the individual component weights and statements.
Initial total weight = 17(18) = 306 kg. Initial X = 3(18) = 54 kg. Weight of Y = 6(18) = 108 kg. Weight of Z = 8(18) = 144 kg. Final total weight = 306 + 30 = 336 kg. Final Y : Z ratio = 108 : 144 = 3 : 4.
Determining all numerical values allows verifying which statements are true.

Anahtar Kavram

Combining three-variable ratio streams into a unified ratio and solving linear rate/proportion equations upon single-component addition.
Soru 2087Soru

A sequence of 24 positive numbers a1,a2,,a24a_1, a_2, \dots, a_{24} is defined by an=120n(n+1)a_n = \frac{120}{n(n+1)} for each integer nn from 11 to 2424. Let T=n=124anT = \sum_{n=1}^{24} a_n be the exact sum of all 24 terms. Which of the following statements must be true? Select all that apply.

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Cevap: The value of TT rounded to the nearest integer is 115115.; The sum of the first 4 terms, n=14an\sum_{n=1}^{4} a_n, represents more than 80%80\% of the total sum TT.

Cevap

The statements confirming that TT rounded to the nearest integer is 115115, and that the sum of the first 4 terms represents more than 80%80\% of TT, are both correct.
The exact sum of the telescoping sequence simplifies to T=120(1125)=115.2T = 120 \left(1 - \frac{1}{25}\right) = 115.2. Rounding 115.2115.2 to the nearest integer gives 115115. Furthermore, the partial sum of the first four terms is 120(115)=96120 \left(1 - \frac{1}{5}\right) = 96, which accounts for 96115.2=5683.33%\frac{96}{115.2} = \frac{5}{6} \approx 83.33\% of the total sum, exceeding 80%80\%.

Adım Adım Çözüm

1
Decompose the sequence formula using partial fractions.
an=120n(n+1)=120(1n1n+1)a_n = \frac{120}{n(n+1)} = 120 \left( \frac{1}{n} - \frac{1}{n+1} \right).
Rewriting the terms as partial fractions converts the sum into a telescoping series.
2
Calculate the exact total sum TT.
T=120[(112)+(1213)++(124125)]=120(1125)=120×0.96=115.2T = 120 \left[ \left(1 - \frac{1}{2}\right) + \left(\frac{1}{2} - \frac{1}{3}\right) + \dots + \left(\frac{1}{24} - \frac{1}{25}\right) \right] = 120 \left(1 - \frac{1}{25}\right) = 120 \times 0.96 = 115.2.
All intermediate terms cancel out, leaving only the first and last components.
3
Evaluate the statement regarding rounding TT to the nearest integer.
115.2115.2 rounded to the nearest integer is 115115, making the rounding statement true.
Since the decimal part .2.2 is less than .5.5, the number rounds down to 115115.
4
Evaluate the sum of the first 4 terms and compare its percentage to TT.
n=14an=120(115)=96\sum_{n=1}^{4} a_n = 120 \left(1 - \frac{1}{5}\right) = 96. The percentage is 96115.2=5683.33%>80%\frac{96}{115.2} = \frac{5}{6} \approx 83.33\% > 80\%.
Comparing 83.33%83.33\% to 80%80\% confirms that the partial sum statement is true.

Anahtar Kavram

Telescoping Series Summation and Percent Estimation
Soru 2088Soru

At a manufacturing facility, the ratio of the daily output of Machine XX to Machine YY is 4:54 : 5, and the ratio of the daily output of Machine YY to Machine ZZ is 3:23 : 2. If the daily output of Machine XX is decreased by 10%10\% and the daily output of Machine ZZ is increased by 25%25\%, what is the new ratio of the daily output of Machine XX to the daily output of Machine ZZ?

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Cevap: 108:125108 : 125

Cevap

The new ratio of the daily output of Machine XX to Machine ZZ is 108:125108 : 125.
The unified ratio of the outputs of the three machines is X:Y:Z=12:15:10X : Y : Z = 12 : 15 : 10. Decreasing Machine XX's output by 10%10\% changes its relative units to 12×0.90=10.812 \times 0.90 = 10.8. Increasing Machine ZZ's output by 25%25\% changes its relative units to 10×1.25=12.510 \times 1.25 = 12.5. Comparing the updated values yields 10.8:12.510.8 : 12.5, which simplifies to 108:125108 : 125.

Adım Adım Çözüm

1
Unify the two separate ratios into a single three-part ratio X:Y:ZX : Y : Z.
Since X:Y=4:5X : Y = 4 : 5 and Y:Z=3:2Y : Z = 3 : 2, multiply X:YX : Y by 33 to get 12:1512 : 15 and multiply Y:ZY : Z by 55 to get 15:1015 : 10. Thus, X:Y:Z=12:15:10X : Y : Z = 12 : 15 : 10.
Machine YY is the common element linking both ratios, so its ratio component must be equalized.
2
Calculate the updated values for XX and ZZ after applying their respective percentage changes.
Machine Xnew=12×(10.10)=12×0.90=10.8X_{new} = 12 \times (1 - 0.10) = 12 \times 0.90 = 10.8. Machine Znew=10×(1+0.25)=10×1.25=12.5Z_{new} = 10 \times (1 + 0.25) = 10 \times 1.25 = 12.5.
Applying a 10%10\% decrease scales a quantity by 0.900.90, while a 25%25\% increase scales it by 1.251.25.
3
Form the ratio Xnew:ZnewX_{new} : Z_{new} and convert to lowest integer terms.
10.8:12.5=10.812.5=10812510.8 : 12.5 = \frac{10.8}{12.5} = \frac{108}{125}, which gives the ratio 108:125108 : 125.
Multiplying both terms by 1010 eliminates decimals, yielding the coprime integer ratio 108:125108 : 125.

Anahtar Kavram

Three-Part Ratio Unification and Relative Percentage Modification
Tahmini Süre:1m 30s
Soru 2089Soru

A research laboratory operates two types of automated centrifuges, Model X and Model Y. A single operating cycle of Model X processes 4040 biological samples and consumes 1010 kilowatt-hours (kWh) of electricity. A single operating cycle of Model Y processes 2525 biological samples and consumes 1515 kWh of electricity. On a given day, the laboratory processed a total of 775775 biological samples and consumed 325325 kWh of electricity using only these two models. What is the total number of operating cycles completed by Model X and Model Y combined on that day?

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Cevap: 25

Cevap

The total number of combined operating cycles completed by Model X and Model Y is 25.
The correct answer is 25. Setting up the linear system 40x+25y=77540x + 25y = 775 and 10x+15y=32510x + 15y = 325 and solving via elimination gives x=10x = 10 cycles for Model X and y=15y = 15 cycles for Model Y. Adding these together gives 10+15=2510 + 15 = 25 total cycles.

Adım Adım Çözüm

1
Define variables and set up the system of linear equations based on total samples and total electricity consumption.
Let xx be the number of cycles for Model X and yy be the number of cycles for Model Y.
System of equations:
1) 40x+25y=77540x + 25y = 775 (Sample constraint)
2) 10x+15y=32510x + 15y = 325 (Energy constraint)
Modeling the word problem as two linear equations in two variables allows for algebraic elimination.
2
Simplify both equations by dividing by their greatest common factors.
Divide Equation 1 by 5: 8x+5y=1558x + 5y = 155
Divide Equation 2 by 5: 2x+3y=652x + 3y = 65
Simplifying coefficients reduces computational complexity and minimizes arithmetic errors.
3
Eliminate variable xx by multiplying the simplified second equation by 4 and subtracting the simplified first equation.
4×(2x+3y=65)8x+12y=2604 \times (2x + 3y = 65) \Rightarrow 8x + 12y = 260
Subtract (8x+5y=155)(8x + 5y = 155):
(8x8x)+(12y5y)=260155(8x - 8x) + (12y - 5y) = 260 - 155
7y=105y=157y = 105 \Rightarrow y = 15
Equalizing the coefficients of xx enables solving directly for yy.
4
Substitute y=15y = 15 back into 2x+3y=652x + 3y = 65 to find xx.
2x+3(15)=652x+45=652x=20x=102x + 3(15) = 65 \Rightarrow 2x + 45 = 65 \Rightarrow 2x = 20 \Rightarrow x = 10
Evaluating xx completes the solution for individual cycle counts.
5
Calculate the requested combined total x+yx + y.
x+y=10+15=25x + y = 10 + 15 = 25
The question specifically requests the sum of operating cycles of both models combined.

Anahtar Kavram

Systems of Linear Equations in Two Variables
Tahmini Süre:1m 45s
Soru 2090Soru

For all non-zero real numbers xx and yy such that xy|x| \neq |y| and x2+2xy+2y20x^2 + 2xy + 2y^2 \neq 0, consider the algebraic expression:

Q(x,y)=x4+4y4x2+2xy+2y2+2x3y2xy3x2y2Q(x, y) = \frac{x^4 + 4y^4}{x^2 + 2xy + 2y^2} + \frac{2x^3 y - 2xy^3}{x^2 - y^2}

Which of the following expressions are equivalent to Q(x,y)Q(x, y)? Indicate all such expressions.

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Cevap: (xy)2+2xy+y2(x - y)^2 + 2xy + y^2; \frac{x^3 + 2xy^2}{x}

Cevap

The expressions equivalent to Q(x,y)Q(x, y) are (xy)2+2xy+y2(x - y)^2 + 2xy + y^2 and x3+2xy2x\frac{x^3 + 2xy^2}{x}.
First, simplify Q(x,y)Q(x, y) by factoring each term. Using Sophie Germain's identity on the numerator of the first term gives x4+4y4=(x2+2y2)2(2xy)2=(x2+2xy+2y2)(x22xy+2y2)x^4 + 4y^4 = (x^2 + 2y^2)^2 - (2xy)^2 = (x^2 + 2xy + 2y^2)(x^2 - 2xy + 2y^2). Dividing this by (x2+2xy+2y2)(x^2 + 2xy + 2y^2) results in x22xy+2y2x^2 - 2xy + 2y^2. For the second term, factoring out 2xy2xy gives 2xy(x2y2)x2y2=2xy\frac{2xy(x^2 - y^2)}{x^2 - y^2} = 2xy. Adding the two simplified terms yields Q(x,y)=(x22xy+2y2)+2xy=x2+2y2Q(x, y) = (x^2 - 2xy + 2y^2) + 2xy = x^2 + 2y^2.

Evaluating the options for equivalence:
- The expression (xy)2+2xy+y2(x - y)^2 + 2xy + y^2 expands to x22xy+y2+2xy+y2=x2+2y2x^2 - 2xy + y^2 + 2xy + y^2 = x^2 + 2y^2.
- The expression x3+2xy2x\frac{x^3 + 2xy^2}{x} factors as x(x2+2y2)x=x2+2y2\frac{x(x^2 + 2y^2)}{x} = x^2 + 2y^2.
Therefore, both of these expressions are equivalent to Q(x,y)Q(x, y).

Adım Adım Çözüm

1
Simplify the first algebraic fraction using Sophie Germain's identity.
x4+4y4x2+2xy+2y2=(x2+2y2)2(2xy)2x2+2xy+2y2=(x2+2xy+2y2)(x22xy+2y2)x2+2xy+2y2=x22xy+2y2\frac{x^4 + 4y^4}{x^2 + 2xy + 2y^2} = \frac{(x^2 + 2y^2)^2 - (2xy)^2}{x^2 + 2xy + 2y^2} = \frac{(x^2 + 2xy + 2y^2)(x^2 - 2xy + 2y^2)}{x^2 + 2xy + 2y^2} = x^2 - 2xy + 2y^2
Completing the square on x4+4y4x^4 + 4y^4 allows it to be factored into the product of two quadratic expressions.
2
Simplify the second algebraic fraction by factoring out common factors.
2x3y2xy3x2y2=2xy(x2y2)x2y2=2xy\frac{2x^3 y - 2xy^3}{x^2 - y^2} = \frac{2xy(x^2 - y^2)}{x^2 - y^2} = 2xy
The term (x2y2)(x^2 - y^2) cancels out since x±yx \neq \pm y.
3
Combine the simplified terms to find the closed-form expression for Q(x,y)Q(x, y).
Q(x,y)=(x22xy+2y2)+2xy=x2+2y2Q(x, y) = (x^2 - 2xy + 2y^2) + 2xy = x^2 + 2y^2
The 2xy-2xy and +2xy+2xy terms sum to zero.
4
Test each option for equivalence to x2+2y2x^2 + 2y^2.
The option (xy)2+2xy+y2(x - y)^2 + 2xy + y^2 expands to x22xy+y2+2xy+y2=x2+2y2x^2 - 2xy + y^2 + 2xy + y^2 = x^2 + 2y^2. The option x3+2xy2x\frac{x^3 + 2xy^2}{x} simplifies directly to x2+2y2x^2 + 2y^2.
Both expressions reduce identically to x2+2y2x^2 + 2y^2 for all non-zero xx and yy.

Anahtar Kavram

Simplifying complex algebraic expressions using polynomial factoring identities (Sophie Germain identity and difference of squares) and algebraic reduction.
Tahmini Süre:2m 0s
Soru 2091Soru

A commercial facility prepares a fruit blend by mixing fruit concentrate with water in a ratio of 3:73:7 by volume. After 15 liters15\text{ liters} of water evaporate from the mixture during processing, the ratio of fruit concentrate to water in the remaining mixture becomes 1:21:2. What was the total volume, in liters, of the original mixture before evaporation?

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Cevap: 150

Cevap

The total volume of the original mixture before evaporation was 150 liters.
Represent the initial concentrate volume as 3x3x liters and the initial water volume as 7x7x liters, making the initial total volume 10x10x liters. Evaporating 1515 liters of water leaves 7x157x - 15 liters of water while the concentrate remains 3x3x liters. Setting the ratio 3x7x15\frac{3x}{7x - 15} equal to 12\frac{1}{2} yields 6x=7x156x = 7x - 15, so x=15x = 15. Substituting x=15x = 15 into the total volume expression 10x10x gives 10(15)=15010(15) = 150 liters.

Adım Adım Çözüm

1
Define initial component volumes using ratio multiplier x
Concentrate volume = 3x3x, Water volume = 7x7x, Total volume = 10x10x
The given initial ratio of concentrate to water is 3:73:7.
2
Formulate equation based on water evaporation and the new ratio
3x7x15=12\frac{3x}{7x - 15} = \frac{1}{2}
Evaporation reduces only the water volume by 15 liters, establishing a new ratio of 1:21:2.
3
Solve the algebraic equation for x
6x=7x15    x=156x = 7x - 15 \implies x = 15
Cross-multiplication simplifies the proportional relationship into a linear equation.
4
Calculate original total volume
10×15=15010 \times 15 = 150 liters
The original total volume is represented by 10x10x.

Anahtar Kavram

Solving component adjustment problems using ratio multipliers
Soru 2092Soru

A sequence of numbers a1,a2,a3,a_1, a_2, a_3, \dots is defined by a1=5a_1 = 5 and an+1=an22a_{n+1} = a_n^2 - 2 for all positive integers n1n \ge 1. Which of the following is the value of the sum n=141an\sum_{n=1}^{4} \frac{1}{a_n}, rounded to the nearest hundredth?

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Cevap: 0.25

Cevap

0.25
Evaluating the recurrence relation yields a1=5a_1 = 5, a2=23a_2 = 23, a3=527a_3 = 527, and a4=277,727a_4 = 277,727. Summing their reciprocals produces 15+123+1527+1277,7270.20+0.043478+0.001898+0.000004=0.24538\frac{1}{5} + \frac{1}{23} + \frac{1}{527} + \frac{1}{277,727} \approx 0.20 + 0.043478 + 0.001898 + 0.000004 = 0.24538. Rounding 0.245380.24538 to the nearest hundredth yields 0.25.

Adım Adım Çözüm

1
Calculate the first four terms of the defined sequence using the recurrence relation an+1=an22a_{n+1} = a_n^2 - 2.
a1=5a_1 = 5, a2=522=23a_2 = 5^2 - 2 = 23, a3=2322=527a_3 = 23^2 - 2 = 527, and a4=52722=277,727a_4 = 527^2 - 2 = 277,727.
The recurrence rule determines each subsequent term from the preceding term.
2
Compute the sum of reciprocals n=141an=15+123+1527+1277,727\sum_{n=1}^{4} \frac{1}{a_n} = \frac{1}{5} + \frac{1}{23} + \frac{1}{527} + \frac{1}{277,727}.
15=0.2\frac{1}{5} = 0.2, 1230.043478\frac{1}{23} \approx 0.043478, 15270.001898\frac{1}{527} \approx 0.001898, and 1277,7270.0000036\frac{1}{277,727} \approx 0.0000036. Sum 0.24538\approx 0.24538.
Converting each fraction term to decimal form allows straightforward addition.
3
Round the calculated sum 0.245380.24538 to the nearest hundredth.
Since the thousandths digit is 55, 0.245380.24538 rounds up to 0.250.25.
Standard rounding rules dictate rounding up when the digit to the right of the target decimal place is 55 or greater.

Anahtar Kavram

Defined sequence terms evaluation, reciprocal sum estimation, and decimal rounding
Tahmini Süre:1m 30s
Soru 2093Soru

A community theater sold a total of 250250 tickets for a performance, consisting of adult tickets for $15\$15 each and student tickets for $10\$10 each. The total revenue collected from ticket sales was $3,100\$3,100. Let aa represent the number of adult tickets sold and ss represent the number of student tickets sold. Which of the following statements must be true? Select all such statements.

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Cevap: The number of student tickets sold was 130130.; The total revenue generated from adult ticket sales was $1,800\$1,800.

Cevap

The correct statements are that the number of student tickets sold was 130, and the total revenue generated from adult ticket sales was $1,800.
The system of equations a+s=250a + s = 250 and 15a+10s=310015a + 10s = 3100 uniquely yields a=120a = 120 adult tickets and s=130s = 130 student tickets. Therefore, the statement that 130 student tickets were sold is true. Furthermore, multiplying 120 adult tickets by their price of 15perticketgivesatotaladultticketrevenueof15 per ticket gives a total adult ticket revenue of 1,800, making that statement true as well.

Adım Adım Çözüm

1
Set up a system of two linear equations in terms of aa and ss.
Equation 1 (total tickets): a+s=250a + s = 250; Equation 2 (total revenue): 15a+10s=310015a + 10s = 3100.
The sum of the ticket quantities equals total tickets, and the sum of monetary contributions equals total revenue.
2
Express ss in terms of aa using Equation 1 and substitute into Equation 2.
s=250a    15a+10(250a)=3100    15a+250010a=3100s = 250 - a \implies 15a + 10(250 - a) = 3100 \implies 15a + 2500 - 10a = 3100.
Using substitution eliminates variable ss to solve for aa.
3
Solve for aa and then find ss.
5a=600    a=1205a = 600 \implies a = 120; s=250120=130s = 250 - 120 = 130.
Dividing 600600 by 55 gives a=120a = 120, and subtracting 120120 from 250250 gives s=130s = 130.
4
Evaluate the statements against the values a=120a = 120 and s=130s = 130.
s=130s = 130 is true. Revenue from adult tickets is 120×15=$1,800120 \times 15 = \$1,800, which is also true.
Comparing calculated values directly confirms which options state accurate quantitative properties.

Anahtar Kavram

Solving 2x2 Systems of Linear Equations using Substitution or Elimination in Word Problems
Soru 2094Soru
Consider the system of linear equations in two variables xx and yy shown below:
3x+2y=16x4y=4\begin{aligned} 3x + 2y &= 16 \\ x - 4y &= -4 \end{aligned}
If (x,y)(x, y) is the unique solution to the system, what is the value of yx\frac{y}{x}?
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Cevap: 12\frac{1}{2}

Cevap

The value of yx\frac{y}{x} is 12\frac{1}{2}.
Solving the system by substitution gives x=4x = 4 and y=2y = 2. Dividing yy by xx gives 24=12\frac{2}{4} = \frac{1}{2}, which is the target ratio.

Adım Adım Çözüm

1
Isolate xx in the second equation.
x=4y4x = 4y - 4
Expressing xx in terms of yy allows for substitution into the first equation.
2
Substitute x=4y4x = 4y - 4 into the first equation.
3(4y4)+2y=16    12y12+2y=16    14y=28    y=23(4y - 4) + 2y = 16 \implies 12y - 12 + 2y = 16 \implies 14y = 28 \implies y = 2
Solving the single-variable equation determines the value of yy.
3
Substitute y=2y = 2 back into the isolated expression for xx.
x=4(2)4=4x = 4(2) - 4 = 4
Determines the corresponding value of xx.
4
Compute the required ratio yx\frac{y}{x}.
yx=24=12\frac{y}{x} = \frac{2}{4} = \frac{1}{2}
Evaluates the final expression requested by the prompt.

Anahtar Kavram

Solving systems of linear equations using substitution or elimination to evaluate a combined expression.
Soru 2095Soru

A chemical processing plant uses two storage tanks, Tank XX and Tank YY. Initially, the ratio of the volume of liquid in Tank XX to Tank YY is 3:73 : 7. After 16 liters16\text{ liters} of liquid are transferred from Tank YY to Tank XX, and an additional 8 liters8\text{ liters} of liquid are added to Tank XX from an external supply, the ratio of the volume of liquid in Tank XX to Tank YY becomes 6:56 : 5. What was the original volume, in liters, of liquid in Tank YY?

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Cevap: 56

Cevap

56 liters
By setting the initial volumes of Tank X and Tank Y to 3k and 7k respectively, the modified volumes after transfer and addition are (3k + 24) and (7k - 16). Setting their ratio equal to 6/5 yields 5(3k + 24) = 6(7k - 16), which simplifies to 27k = 216, or k = 8. Multiplying 8 by 7 gives the original volume of Tank Y as 56 liters.

Adım Adım Çözüm

1
Define initial quantities using a common ratio multiplier kk.
Let the initial volume of Tank XX be 3k3k liters and the initial volume of Tank YY be 7k7k liters.
The given initial ratio of X:YX : Y is 3:73 : 7.
2
Express the new volumes after the liquid transfers.
Tank XX volume becomes 3k+16+8=3k+243k + 16 + 8 = 3k + 24 liters. Tank YY volume becomes 7k167k - 16 liters.
Transferring 16 liters16\text{ liters} from Tank YY to Tank XX decreases Tank YY by 1616 and increases Tank XX by 1616. Adding an extra 8 liters8\text{ liters} to Tank XX brings its total increase to 24 liters24\text{ liters}.
3
Set up the proportion with the new ratio and solve for kk.
\begin{aligned} \frac{3k + 24}{7k - 16} &= \frac{6}{5} \\[6pt] 5(3k + 24) &= 6(7k - 16) \\[6pt] 15k + 120 &= 42k - 96 \\[6pt] 216 &= 27k \\[6pt] k &= 8 \end{aligned}
The new ratio of Tank XX to Tank YY is given as 6:56 : 5.
4
Calculate the original volume of Tank YY.
Original volume of Tank Y=7k=7×8=56 litersY = 7k = 7 \times 8 = 56\text{ liters}.
Tank YY initially contained 7k7k liters.

Anahtar Kavram

Algebraic setup of part-to-part ratios undergoing quantitative adjustments
Tahmini Süre:1m 30s
Soru 2096Soru

A sequence of numbers a1,a2,a3,a_1, a_2, a_3, \dots is defined by a1=50a_1 = 50 and an+1=13an+15a_{n+1} = \frac{1}{3} a_n + 15 for all positive integers n1n \ge 1. Each term ana_n is rounded to the nearest integer to produce a secondary sequence bnb_n. What is the value of n=14bn\sum_{n=1}^{4} b_n?

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Cevap: 132

Cevap

132
Evaluating each term yields a1=50a_1 = 50, a2=31.6667...a_2 = 31.6667..., a3=25.5556...a_3 = 25.5556..., and a4=23.5185...a_4 = 23.5185.... Rounding each term individually to the nearest integer gives b1=50b_1 = 50, b2=32b_2 = 32, b3=26b_3 = 26, and b4=24b_4 = 24. Their sum is 50+32+26+24=13250 + 32 + 26 + 24 = 132.

Adım Adım Çözüm

1
Calculate the exact value of the first term a1a_1 and its rounded value b1b_1.
a1=50a_1 = 50, which is an integer. Thus, b1=50b_1 = 50.
Given initial value.
2
Calculate the exact value of a2a_2 using the recursive formula a2=13a1+15a_2 = \frac{1}{3}a_1 + 15 and round to nearest integer.
a2=13(50)+15=503+15=31.6667...a_2 = \frac{1}{3}(50) + 15 = \frac{50}{3} + 15 = 31.6667.... Rounding to the nearest integer gives b2=32b_2 = 32.
Apply sequence relation and rounding rule.
3
Calculate the exact value of a3=13a2+15a_3 = \frac{1}{3}a_2 + 15 and round to nearest integer.
a3=13(953)+15=959+15=2309=25.5556...a_3 = \frac{1}{3}\left(\frac{95}{3}\right) + 15 = \frac{95}{9} + 15 = \frac{230}{9} = 25.5556.... Rounding to the nearest integer gives b3=26b_3 = 26.
Apply sequence relation and rounding rule.
4
Calculate the exact value of a4=13a3+15a_4 = \frac{1}{3}a_3 + 15 and round to nearest integer.
a4=13(2309)+15=23027+15=63527=23.5185...a_4 = \frac{1}{3}\left(\frac{230}{9}\right) + 15 = \frac{230}{27} + 15 = \frac{635}{27} = 23.5185.... Rounding to the nearest integer gives b4=24b_4 = 24.
Apply sequence relation and rounding rule.
5
Sum the four rounded terms b1+b2+b3+b4b_1 + b_2 + b_3 + b_4.
n=14bn=50+32+26+24=132\sum_{n=1}^{4} b_n = 50 + 32 + 26 + 24 = 132.
Add the individual rounded terms.

Anahtar Kavram

Recursive sequence evaluation and term-by-term rounding vs total sum rounding.
Soru 2097Soru

A commercial print shop operates two types of high-speed printers, Printer M and Printer N. Operating simultaneously for 55 hours, 22 units of Printer M and 33 units of Printer N print a total of 5,5005,500 pages. Operating simultaneously for 44 hours, 55 units of Printer M and 22 units of Printer N print a total of 6,6006,600 pages. What is the hourly page output of a single Printer M?

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Cevap: 250

Cevap

The hourly page output of a single Printer M is 250 pages per hour.
Dividing each total page output by the corresponding number of hours produces the simplified linear system: 2m+3n=11002m + 3n = 1100 and 5m+2n=16505m + 2n = 1650, where mm and nn are the hourly rates of Printer M and Printer N. Multiplying the first equation by 22 gives 4m+6n=22004m + 6n = 2200, and multiplying the second equation by 33 gives 15m+6n=495015m + 6n = 4950. Subtracting the two equations eliminates nn, giving 11m=275011m = 2750, which simplifies to m=250m = 250 pages per hour.

Adım Adım Çözüm

1
Define variables and write initial algebraic equations based on time and rate.
Let mm represent the hourly page output of Printer M and nn represent the hourly page output of Printer N. The total outputs give 5(2m+3n)=55005(2m + 3n) = 5500 and 4(5m+2n)=66004(5m + 2n) = 6600.
Total page output equals total operating time multiplied by the combined hourly output rate.
2
Simplify the system by dividing each equation by its respective number of hours.
First equation: 2m+3n=11002m + 3n = 1100. Second equation: 5m+2n=16505m + 2n = 1650.
Simplifying yields a standard system of linear equations representing the combined hourly rate.
3
Eliminate variable nn to solve for mm.
Multiply 2m+3n=11002m + 3n = 1100 by 22 to get 4m+6n=22004m + 6n = 2200. Multiply 5m+2n=16505m + 2n = 1650 by 33 to get 15m+6n=495015m + 6n = 4950. Subtracting the first modified equation from the second yields 11m=275011m = 2750, so m=250m = 250.
Equating the coefficients of nn allows direct elimination of nn when subtracting the equations.

Anahtar Kavram

Solving a 2x2 system of linear equations using the method of elimination
Tahmini Süre:1m 30s
Soru 2098Soru
For all real numbers x5x \neq -5, the algebraic expression
x3+125x25x+25x225x+5\frac{x^3 + 125}{x^2 - 5x + 25} - \frac{x^2 - 25}{x + 5}
simplifies to a single constant value. What is the value of this constant?
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Cevap: 10

Cevap

The simplified value of the expression for all valid real numbers x is 10.
Factoring the numerators reveals that the first term reduces to x+5x + 5 and the second term reduces to x5x - 5. Subtracting (x5)(x - 5) from (x+5)(x + 5) yields (x+5)(x5)=10(x + 5) - (x - 5) = 10, which is constant for all valid values of xx.

Adım Adım Çözüm

1
Factor the numerator of the first rational term using the sum of cubes identity.
x3+125=(x+5)(x25x+25)x^3 + 125 = (x + 5)(x^2 - 5x + 25)
The sum of cubes formula a3+b3=(a+b)(a2ab+b2)a^3 + b^3 = (a + b)(a^2 - ab + b^2) applies with a=xa = x and b=5b = 5.
2
Cancel the non-zero factor (x25x+25)(x^2 - 5x + 25) from the first fraction.
\frac{(x + 5)(x^2 - 5x + 25)}{x^2 - 5x + 25} = x + 5
The quadratic factor x25x+25x^2 - 5x + 25 has a negative discriminant ((5)24(1)(25)=75<0(-5)^2 - 4(1)(25) = -75 < 0), so it is never zero for any real number xx.
3
Factor the numerator of the second rational term using the difference of squares identity.
x225=(x5)(x+5)x^2 - 25 = (x - 5)(x + 5)
The difference of squares formula a2b2=(ab)(a+b)a^2 - b^2 = (a - b)(a + b) applies with a=xa = x and b=5b = 5.
4
Cancel the common factor (x+5)(x + 5) from the second fraction.
\frac{(x - 5)(x + 5)}{x + 5} = x - 5
Given x5x \neq -5, the factor x+5x + 5 is non-zero and can be canceled.
5
Subtract the two simplified terms.
(x+5)(x5)=x+5x+5=10(x + 5) - (x - 5) = x + 5 - x + 5 = 10
Distribute the negative sign to both terms in (x5)(x - 5) and combine like terms.

Anahtar Kavram

Factoring sum of cubes and difference of squares to simplify rational expressions
Soru 2099Soru

A courier travels along a straight route from Office P to Office Q at a constant speed r1r_1, and immediately returns along the exact same route from Office Q to Office P at a constant speed r2r_2. The ratio of the outbound speed to the return speed is r1:r2=3:2r_1 : r_2 = 3 : 2. Which of the following statements must be true? Select all such statements.

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Cevap: The time spent on the return trip is 50%50\% greater than the time spent on the outbound trip.; The average speed for the entire round trip is equal to 80%80\% of the outbound speed.

Cevap

The statement that the return trip time is 50 percent greater than the outbound trip time, and the statement that the average speed for the entire round trip is equal to 80 percent of the outbound speed.
The return trip time is 50%50\% greater than the outbound trip time because speed and time are inversely proportional over equal distances (t1:t2=2:3t_1 : t_2 = 2 : 3). Additionally, the overall average speed is 12k5=2.4k\frac{12k}{5} = 2.4k, which is precisely 80%80\% of the outbound speed (3k3k).

Adım Adım Çözüm

1
Express travel times in terms of distance DD and rate multiplier kk.
Let outbound speed r1=3kr_1 = 3k and return speed r2=2kr_2 = 2k. Outbound time t1=D3kt_1 = \frac{D}{3k} and return time t2=D2kt_2 = \frac{D}{2k}. The ratio of times t1:t2=D/3kD/2k=2:3t_1 : t_2 = \frac{D/3k}{D/2k} = 2 : 3.
Time equals distance divided by rate, establishing an inverse relationship between speed and time for constant distance.
2
Evaluate the relative difference between return time and outbound time.
Return time t2=1.5t1t_2 = 1.5 t_1, which means t2t_2 is 50%50\% greater than t1t_1.
A factor of 1.51.5 represents a 50%50\% increase over the base value t1t_1.
3
Calculate the average speed RavgR_{\text{avg}} for the round trip.
Total distance is 2D2D, and total time is t1+t2=D3k+D2k=5D6kt_1 + t_2 = \frac{D}{3k} + \frac{D}{2k} = \frac{5D}{6k}. Thus, Ravg=2D5D6k=12k5=2.4kR_{\text{avg}} = \frac{2D}{\frac{5D}{6k}} = \frac{12k}{5} = 2.4k.
Average speed is defined as total distance divided by total elapsed time.
4
Compare RavgR_{\text{avg}} to the outbound speed r1r_1 and the arithmetic mean of rates.
Ravgr1=2.4k3k=0.80=80%\frac{R_{\text{avg}}}{r_1} = \frac{2.4k}{3k} = 0.80 = 80\%. The arithmetic mean is 3k+2k2=2.5k2.4k\frac{3k + 2k}{2} = 2.5k \neq 2.4k. Outbound time fraction is t1t1+t2=25=40%\frac{t_1}{t_1 + t_2} = \frac{2}{5} = 40\%.
Unweighted arithmetic averaging fails for rates over equal distances because more time is spent traveling at the lower speed.

Anahtar Kavram

Inverse proportion between speed and time, harmonic mean for round-trip average speed, and part-to-whole time ratios.
Tahmini Süre:2m 0s
Soru 2100Soru

Working alone at their respective constant rates, Machine AA can complete a production order in 6 hours6\text{ hours}, Machine BB in 8 hours8\text{ hours}, and Machine CC in 12 hours12\text{ hours}. All three machines start working together on the order at 9:00 AM. At 10:00 AM, Machine AA breaks down and stops working, while Machines BB and CC continue working together at their constant rates until the order is completed. At what time will the production order be completed?

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Cevap: 1:00 PM

Cevap

The production order will be completed at 1:00 PM.
The option specifying 1:00 PM is correct because during the first hour (9:00 AM to 10:00 AM), all three machines work together and complete 16+18+112=38\frac{1}{6} + \frac{1}{8} + \frac{1}{12} = \frac{3}{8} of the job. This leaves 58\frac{5}{8} of the job remaining at 10:00 AM. Machines B and C work together at a rate of 18+112=524\frac{1}{8} + \frac{1}{12} = \frac{5}{24} of the job per hour. Dividing the remaining work (58\frac{5}{8}) by this combined rate (524\frac{5}{24}) gives exactly 3 hours. Adding 3 hours to 10:00 AM yields 1:00 PM.

Adım Adım Çözüm

1
Calculate individual work rates for each machine.
Machine A rate = 16\frac{1}{6} order/hr, Machine B rate = 18\frac{1}{8} order/hr, Machine C rate = 112\frac{1}{12} order/hr.
Work rate is defined as job completed per unit of time.
2
Calculate the work completed by all three machines from 9:00 AM to 10:00 AM (1 hour).
Combined rate = 16+18+112=4+3+224=924=38\frac{1}{6} + \frac{1}{8} + \frac{1}{12} = \frac{4 + 3 + 2}{24} = \frac{9}{24} = \frac{3}{8} of the order.
All three machines work together for exactly 1 hour.
3
Determine the remaining fraction of the order after 10:00 AM.
Remaining work = 138=581 - \frac{3}{8} = \frac{5}{8} of the order.
Subtract completed work from the total work (1 whole order).
4
Calculate the combined rate of Machines B and C.
Combined rate of B and C = 18+112=3+224=524\frac{1}{8} + \frac{1}{12} = \frac{3 + 2}{24} = \frac{5}{24} order/hr.
Machine A stops, leaving only B and C working.
5
Calculate the additional time needed to complete the remaining work.
Time = 5/85/24=58×245=3 hours\frac{5/8}{5/24} = \frac{5}{8} \times \frac{24}{5} = 3\text{ hours}.
Divide remaining work by the combined rate of the remaining active machines.
6
Add the additional time to the breakdown time (10:00 AM).
Completion time = 10:00 AM + 3 hours = 1:00 PM.
The remaining work begins at 10:00 AM when Machine A breaks down.

Anahtar Kavram

Combined Work Rates and Staggered Work Times
ÖncekiSayfa 105 / 107Sonraki
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