Fractions and Rational Numbers

32 soru

Soru 1Soru

Which of the following rational numbers are strictly greater than 35\frac{3}{5}? Select all that apply.

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Cevap: 710\frac{7}{10}; 23\frac{2}{3}; 1115\frac{11}{15}

Cevap

The fractions greater than 3/5 are 7/10, 2/3, and 11/15.
Converting 3/5 to decimal form yields 0.60. Evaluating the options: 7/10 equals 0.70, 2/3 is approximately 0.667, and 11/15 is approximately 0.733. Because each of these three values is strictly greater than 0.60, all three are correct choices.

Adım Adım Çözüm

1
Convert the benchmark fraction 3/5 to decimal form.
3/5 = 0.60.
Decimal conversion provides a clear standard for comparing rational numbers.
2
Convert each given choice to decimal form and compare it to 0.60.
7/10 = 0.70; 2/3 ≈ 0.667; 5/9 ≈ 0.556; 4/7 ≈ 0.571; 11/15 ≈ 0.733.
Direct comparison reveals which decimals exceed 0.60.
3
Select all fractions whose values exceed 0.60.
The values 0.70, 0.667, and 0.733 are all strictly greater than 0.60.
The corresponding fractions 7/10, 2/3, and 11/15 satisfy the given condition.

Anahtar Kavram

Comparing Rational Numbers and Fractions
Soru 2Soru

A baker has a flour mixture consisting only of wheat flour and rye flour. Currently, wheat flour accounts for 25\frac{2}{5} of the total weight of the mixture. If the baker adds 99 pounds of wheat flour to the mixture, wheat flour will account for 12\frac{1}{2} of the new total weight of the mixture. What was the total weight, in pounds, of the original flour mixture?

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Cevap: 45

Cevap

The total weight of the original flour mixture was 45 pounds.
The initial total weight of the mixture is 45 pounds. Initially, wheat flour makes up 25×45=18\frac{2}{5} \times 45 = 18 pounds. Adding 9 pounds of wheat flour increases the wheat flour to 18+9=2718 + 9 = 27 pounds and the total weight to 45+9=5445 + 9 = 54 pounds. The new fraction of wheat flour is 2754=12\frac{27}{54} = \frac{1}{2}, which satisfies the given conditions.

Adım Adım Çözüm

1
Express the initial weight of wheat flour in terms of the initial total weight WW.
Initial weight of wheat flour = 25W\frac{2}{5}W.
Wheat flour represents 25\frac{2}{5} of the total mixture.
2
Formulate an equation reflecting the addition of 9 pounds of wheat flour.
\frac{\frac{2}{5}W + 9}{W + 9} = \frac{1}{2}
Adding 9 pounds of wheat flour increases both the amount of wheat flour and the total weight of the mixture by 9 pounds.
3
Solve the algebraic equation for WW.
Cross-multiplying gives 2(25W+9)=W+92\left(\frac{2}{5}W + 9\right) = W + 9, which simplifies to 45W+18=W+9\frac{4}{5}W + 18 = W + 9. Subtracting 45W\frac{4}{5}W and 99 from both sides gives 15W=9\frac{1}{5}W = 9, so W=45W = 45.
Isolating WW gives the value of the original total weight.

Anahtar Kavram

Setting up and solving equations involving fractional parts when a quantity is added to both the part and the whole.
Soru 3Soru

A budget planner allocates 13\frac{1}{3} of a monthly stipend to housing expenses and 25\frac{2}{5} of the stipend to food. If no other expenses are incurred from these two categories, what fraction of the total monthly stipend remains unallocated?

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Cevap: 415\frac{4}{15}

Cevap

415\frac{4}{15} of the total monthly stipend remains unallocated.
To find the remaining unallocated fraction, first determine the total fraction spent by adding 13\frac{1}{3} and 25\frac{2}{5} using the common denominator 1515, yielding 515+615=1115\frac{5}{15} + \frac{6}{15} = \frac{11}{15}. Subtracting this total from 11 gives 11115=4151 - \frac{11}{15} = \frac{4}{15}. Thus, the option equal to 415\frac{4}{15} is correct.

Adım Adım Çözüm

1
Calculate the total fraction allocated to housing and food.
13+25=515+615=1115\frac{1}{3} + \frac{2}{5} = \frac{5}{15} + \frac{6}{15} = \frac{11}{15}
Find a common denominator (15) to combine the fractions.
2
Subtract the allocated fraction from 1 to determine the unallocated portion.
1 - \frac{11}{15} = \frac{15}{15} - \frac{11}{15} = \frac{4}{15}
The total stipend is represented by 1 whole.

Anahtar Kavram

Adding and subtracting rational numbers using common denominators
Tahmini Süre:1m 0s
Soru 4Soru

An artist sold 13\frac{1}{3} of her paintings on the first day of an exhibition. On the second day, she sold 25\frac{2}{5} of the paintings that remained after the first day. On the third day, she sold 14\frac{1}{4} of the paintings that remained after the second day. If 1818 paintings remained unsold at the end of the third day, how many paintings did the artist have originally?

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Cevap: 60

Cevap

The artist originally had 60 paintings.
To find the original total, determine the remaining fraction of paintings after each day sequentially. After day one, 23\frac{2}{3} remain. After day two, 35\frac{3}{5} of 23\frac{2}{3} remain, which is 25\frac{2}{5}. After day three, 34\frac{3}{4} of 25\frac{2}{5} remain, which simplifies to 310\frac{3}{10} of the original total. Given that 310\frac{3}{10} of the total equals 1818, dividing 1818 by 310\frac{3}{10} gives 6060.

Adım Adım Çözüm

1
Calculate the fraction of paintings remaining after the first day.
Remaining fraction after Day 1 = 113=231 - \frac{1}{3} = \frac{2}{3}.
Selling 13\frac{1}{3} of the total leaves 23\frac{2}{3} of the original total.
2
Calculate the fraction of paintings remaining after the second day.
Remaining fraction after Day 2 = 23×(125)=23×35=25\frac{2}{3} \times \left(1 - \frac{2}{5}\right) = \frac{2}{3} \times \frac{3}{5} = \frac{2}{5}.
Selling 25\frac{2}{5} of the remaining paintings leaves 35\frac{3}{5} of that remaining portion.
3
Calculate the fraction of paintings remaining after the third day.
Remaining fraction after Day 3 = 25×(114)=25×34=620=310\frac{2}{5} \times \left(1 - \frac{1}{4}\right) = \frac{2}{5} \times \frac{3}{4} = \frac{6}{20} = \frac{3}{10}.
Selling 14\frac{1}{4} of the remaining paintings leaves 34\frac{3}{4} of the second day's remaining portion.
4
Set up the equation with the given remaining quantity and solve for the total number of paintings NN.
310N=18    N=18×103=60\frac{3}{10} N = 18 \implies N = 18 \times \frac{10}{3} = 60.
The final remaining fraction represents 1818 paintings.

Anahtar Kavram

Sequential Fraction of Remainder Problems
Soru 5Soru

At a certain technology company, 49\frac{4}{9} of the employees work in the sales department and 13\frac{1}{3} of the employees work in the engineering department. If all of the remaining employees work in the administration department, what fraction of the total employees works in the administration department?

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Cevap: 29\frac{2}{9}

Cevap

29\frac{2}{9}
Expressing 13\frac{1}{3} as 39\frac{3}{9} allows direct addition with 49\frac{4}{9}, giving 79\frac{7}{9} for sales and engineering combined. Subtracting 79\frac{7}{9} from 1 leaves 29\frac{2}{9} for administration.

Adım Adım Çözüm

1
Find the total fraction of employees working in sales and engineering.
49+13=49+39=79\frac{4}{9} + \frac{1}{3} = \frac{4}{9} + \frac{3}{9} = \frac{7}{9}
Convert 13\frac{1}{3} to an equivalent fraction with a common denominator of 9 before adding.
2
Subtract the combined fraction from 1 to find the remaining fraction.
179=9979=291 - \frac{7}{9} = \frac{9}{9} - \frac{7}{9} = \frac{2}{9}
The sum of all departmental fractions must equal 1 whole.

Anahtar Kavram

Adding fractions with unlike denominators and determining the remaining part of a whole.
Soru 6Soru

If xx and yy are non-zero rational numbers such that xy<12\frac{x}{y} < -\frac{1}{2} and x+y>0x + y > 0, which of the following statements must be true? Select all that apply.

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Cevap: xy<0xy < 0; 1x+1y<0\frac{1}{x} + \frac{1}{y} < 0; x2+y2>(x+y)2x^2 + y^2 > (x+y)^2

Cevap

The statements xy<0xy < 0, 1x+1y<0\frac{1}{x} + \frac{1}{y} < 0, and x2+y2>(x+y)2x^2 + y^2 > (x+y)^2 must be true.
Because xy<12\frac{x}{y} < -\frac{1}{2}, xx and yy must carry opposite algebraic signs, establishing that xy<0xy < 0. Combining the reciprocals into x+yxy\frac{x+y}{xy} places a positive numerator over a negative denominator, ensuring the sum of reciprocals is strictly negative. Expanding (x+y)2=x2+y2+2xy(x+y)^2 = x^2 + y^2 + 2xy shows that adding the negative term 2xy2xy makes (x+y)2<x2+y2(x+y)^2 < x^2 + y^2.

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1
Determine the sign of the product xyxy
xy<0xy < 0
The quotient of two non-zero real numbers is negative if and only if they have opposite signs. Since xy<12<0\frac{x}{y} < -\frac{1}{2} < 0, xx and yy must have opposite signs, so their product is negative.
2
Evaluate the sum of reciprocals 1x+1y\frac{1}{x} + \frac{1}{y}
1x+1y<0\frac{1}{x} + \frac{1}{y} < 0
Finding a common denominator gives 1x+1y=x+yxy\frac{1}{x} + \frac{1}{y} = \frac{x+y}{xy}. Given x+y>0x+y > 0 (positive) and xy<0xy < 0 (negative), dividing a positive number by a negative number yields a negative result.
3
Compare x2+y2x^2 + y^2 with (x+y)2(x+y)^2
x2+y2>(x+y)2x^2 + y^2 > (x+y)^2
Using algebraic expansion, (x+y)2=x2+y2+2xy(x+y)^2 = x^2 + y^2 + 2xy. Because xy<0xy < 0, 2xy2xy is negative. Subtracting a positive value (or adding a negative value) to x2+y2x^2 + y^2 results in a smaller quantity.
4
Test counterexamples for x>yx > y and x>y|x| > |y|
Neither statement is required to be true.
Let x=2x = -2 and y=3y = 3. Both are rational numbers. Check conditions: 23<12\frac{-2}{3} < -\frac{1}{2} holds, and 2+3=1>0-2 + 3 = 1 > 0 holds. For this counterexample, x=2<3=yx = -2 < 3 = y and 2=2<3=y|-2| = 2 < 3 = |y|.

Anahtar Kavram

Signs and inequalities of rational numbers and reciprocal operations
Soru 7Soru

A chemical storage vessel contains a mixture composed of three liquid components: Component XX, Component YY, and Component ZZ. Initially, Component XX accounts for 38\frac{3}{8} of the total mixture volume, and Component YY accounts for 512\frac{5}{12} of the total mixture volume, with Component ZZ occupying the remainder of the volume.

During a processing stage, 13\frac{1}{3} of Component XX is extracted and 25\frac{2}{5} of Component YY is extracted, while Component ZZ remains completely unchanged. If the total volume of the mixture remaining in the vessel after processing is 170 milliliters, what was the total volume, in milliliters, of the mixture in the vessel before processing?

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Cevap: 240

Cevap

The initial total volume of the mixture was 240 milliliters.
To find the initial total volume, first find the fraction of the initial mixture that is Component Z: 1(3/8+5/12)=5/241 - (3/8 + 5/12) = 5/24. Next, compute the remaining amounts of each component relative to the initial total volume VV: Component X has (11/3)×3/8=1/4=6/24(1 - 1/3) \times 3/8 = 1/4 = 6/24 remaining; Component Y has (12/5)×5/12=1/4=6/24(1 - 2/5) \times 5/12 = 1/4 = 6/24 remaining; Component Z retains its 5/245/24. Summing these yields 6/24+6/24+5/24=17/246/24 + 6/24 + 5/24 = 17/24 of the original volume. Setting (17/24)V=170(17/24)V = 170 mL gives V=170×(24/17)=240V = 170 \times (24/17) = 240 mL.

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1
Find the initial fraction of the mixture representing Component ZZ.
Component Z=1(38+512)=1(924+1024)=11924=524Z = 1 - \left(\frac{3}{8} + \frac{5}{12}\right) = 1 - \left(\frac{9}{24} + \frac{10}{24}\right) = 1 - \frac{19}{24} = \frac{5}{24}.
The sum of all component fractions must equal 1.
2
Calculate the remaining fraction for each component relative to the initial total volume VV.
Remaining X=(113)×38V=23×38V=14V=624VX = \left(1 - \frac{1}{3}\right) \times \frac{3}{8}V = \frac{2}{3} \times \frac{3}{8}V = \frac{1}{4}V = \frac{6}{24}V.
Remaining Y=(125)×512V=35×512V=14V=624VY = \left(1 - \frac{2}{5}\right) \times \frac{5}{12}V = \frac{3}{5} \times \frac{5}{12}V = \frac{1}{4}V = \frac{6}{24}V.
Remaining Z=524VZ = \frac{5}{24}V.
When a fraction of a component is removed, the remaining fraction of that component is multiplied by its original portion of the total mixture.
3
Sum the remaining component fractions to find the total remaining volume as a fraction of VV.
Total Remaining Fraction =624V+624V+524V=1724V= \frac{6}{24}V + \frac{6}{24}V + \frac{5}{24}V = \frac{17}{24}V.
Combining the remaining amounts gives the fraction of the initial mixture left.
4
Solve for the initial total volume VV using the given final volume of 170 mL.
\frac{17}{24}V = 170 \implies V = 170 \times \frac{24}{17} = 10 \times 24 = 240 \text{ mL}.
Multiplying the final volume by the reciprocal of the remaining fraction yields the original volume.

Anahtar Kavram

Multi-step fraction operations and solving for original whole amounts
Soru 8Soru

A logistics company received a shipment of identical freight containers. On Monday, the crew unloaded 27\frac{2}{7} of the total shipment. On Tuesday, they unloaded 35\frac{3}{5} of the remaining containers. On Wednesday, they unloaded 12\frac{1}{2} of the containers that remained after Tuesday's work. If 30 containers remained unloaded at the end of Wednesday, what was the total number of containers in the original shipment?

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Cevap: 210

Cevap

The total number of containers in the original shipment was 210.
The correct answer is 210. Working forward, after Monday 57\frac{5}{7} of the initial shipment NN remains. On Tuesday, 25\frac{2}{5} of that remainder stays unloaded, which equals 25×57N=27N\frac{2}{5} \times \frac{5}{7}N = \frac{2}{7}N. On Wednesday, 12\frac{1}{2} of that remainder stays unloaded, yielding 12×27N=17N\frac{1}{2} \times \frac{2}{7}N = \frac{1}{7}N. Setting 17N=30\frac{1}{7}N = 30 gives N=210N = 210.

Adım Adım Çözüm

1
Determine the fraction of containers remaining after Monday.
Since 27\frac{2}{7} of the total shipment NN was unloaded on Monday, the fraction remaining is 127=571 - \frac{2}{7} = \frac{5}{7} of NN.
Subtracting the fraction unloaded on Monday from 1 gives the remaining fraction.
2
Calculate the fraction of containers remaining after Tuesday.
On Tuesday, 35\frac{3}{5} of the remaining 57N\frac{5}{7}N was unloaded, which is 35×57N=37N\frac{3}{5} \times \frac{5}{7}N = \frac{3}{7}N. The remaining fraction after Tuesday is 57N37N=27N\frac{5}{7}N - \frac{3}{7}N = \frac{2}{7}N.
Alternatively, if 35\frac{3}{5} of the remainder was unloaded, then 135=251 - \frac{3}{5} = \frac{2}{5} of the remainder was left: 25×57N=27N\frac{2}{5} \times \frac{5}{7}N = \frac{2}{7}N.
3
Calculate the fraction of containers remaining after Wednesday.
On Wednesday, 12\frac{1}{2} of the remaining 27N\frac{2}{7}N was unloaded, leaving 112=121 - \frac{1}{2} = \frac{1}{2} of that remainder. Thus, the final fraction remaining is 12×27N=17N\frac{1}{2} \times \frac{2}{7}N = \frac{1}{7}N.
Multiplying the remaining fraction after Tuesday by the fraction left unhandled on Wednesday yields the overall fraction of the original shipment remaining.
4
Solve for the total initial number of containers NN.
Set 17N=30\frac{1}{7}N = 30, which gives N=30×7=210N = 30 \times 7 = 210.
Equating the calculated final remaining fraction to the given numerical count allows solving for the total original quantity.

Anahtar Kavram

Sequential Fraction of Remaining Quantities
Soru 9Soru

A container originally holds a liquid mixture in which 25\frac{2}{5} of the total volume is pure juice. After 66 liters of pure juice are added to the container, pure juice makes up 12\frac{1}{2} of the new total volume. How many liters of mixture were originally in the container?

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Cevap: 30

Cevap

30 liters
The original mixture volume VV contains 25V\frac{2}{5}V liters of pure juice. When 66 liters of pure juice are added, the new volume of juice becomes 25V+6\frac{2}{5}V + 6 and the new total volume becomes V+6V + 6. Setting 25V+6=12(V+6)\frac{2}{5}V + 6 = \frac{1}{2}(V + 6) leads to 110V=3\frac{1}{10}V = 3, giving V=30V = 30 liters.

Adım Adım Çözüm

1
Define variables for the original volume and pure juice volume.
Let VV represent the original volume of the mixture in liters. The original volume of pure juice is 25V\frac{2}{5}V.
Expressing the initial quantity of juice in terms of the unknown total volume establishes the baseline algebraic relationship.
2
Set up an equation incorporating the added quantity of pure juice.
New juice volume =25V+6= \frac{2}{5}V + 6, and new total volume =V+6= V + 6. The equation is 25V+6=12(V+6)\frac{2}{5}V + 6 = \frac{1}{2}(V + 6).
Adding pure juice increases both the pure juice component and the total volume of the mixture by 66 liters.
3
Solve the linear equation for VV.
Expanding the right side gives 25V+6=12V+3\frac{2}{5}V + 6 = \frac{1}{2}V + 3. Subtracting 25V\frac{2}{5}V from both sides gives 63=(1225)V3=110VV=306 - 3 = \left(\frac{1}{2} - \frac{2}{5}\right)V \Rightarrow 3 = \frac{1}{10}V \Rightarrow V = 30.
Finding a common denominator for the fractions 12=510\frac{1}{2} = \frac{5}{10} and 25=410\frac{2}{5} = \frac{4}{10} allows solving for VV directly.

Anahtar Kavram

Solving linear equations involving fractions of whole quantities and mixture relationships.
Tahmini Süre:1m 0s
Soru 10Soru

A storage tank is initially 23\frac{2}{3} full of liquid. After 14\frac{1}{4} of the liquid inside the tank is drained out, 1515 gallons of liquid are added to the tank. If the tank is then 56\frac{5}{6} full, what is the total capacity of the tank, in gallons?

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Cevap: 45

Cevap

45 gallons
The correct answer of 45 gallons is found by calculating the liquid remaining after draining 14\frac{1}{4} of the initial 23C\frac{2}{3} C, which leaves 12C\frac{1}{2} C. Adding 15 gallons brings the total volume to 56C\frac{5}{6} C. Solving 56C12C=15\frac{5}{6} C - \frac{1}{2} C = 15 gives 13C=15\frac{1}{3} C = 15, so C=45C = 45.

Adım Adım Çözüm

1
Determine the fraction of liquid in the tank after draining.
The initial amount of liquid is 23C\frac{2}{3} C, where CC is the total capacity. Draining 14\frac{1}{4} of this liquid leaves 114=341 - \frac{1}{4} = \frac{3}{4} of the initial liquid. Thus, the remaining liquid is 34×23C=12C\frac{3}{4} \times \frac{2}{3} C = \frac{1}{2} C.
The fraction drained applies to the existing liquid volume, not the total container capacity.
2
Set up an equation incorporating the added liquid and final tank fraction.
12C+15=56C\frac{1}{2} C + 15 = \frac{5}{6} C
Adding 1515 gallons to the remaining liquid yields a volume equal to 56\frac{5}{6} of the total capacity.
3
Solve for the total capacity CC.
Subtracting 12C\frac{1}{2} C (which is 36C\frac{3}{6} C) from both sides gives 15=56C36C=26C=13C15 = \frac{5}{6} C - \frac{3}{6} C = \frac{2}{6} C = \frac{1}{3} C. Multiplying both sides by 33 yields C=45C = 45.
Isolating CC determines the overall volume of the tank.

Anahtar Kavram

Multi-step operations with fractions and fractional parts of a whole
Tahmini Süre:1m 30s
Soru 11Soru

A laboratory vessel contains a liquid solution consisting of water and ethanol, where water makes up 38\frac{3}{8} of the total volume. First, 15\frac{1}{5} of the total volume of the solution is drained and replaced with an equal volume of pure ethanol. Next, 14\frac{1}{4} of the resulting mixture is evaporated, removing water and ethanol in proportion to their presence. Finally, pure water is added to fill the vessel back to its original total volume. What fraction of the final solution is water? Express your answer as a decimal.

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Cevap: 0.475

Cevap

The fraction of the final solution that is water is 0.475 (or 19/40).
By following the multi-step fractional changes to the liquid volume, the remaining water prior to refilling is 940\frac{9}{40} of the original capacity. Refilling the missing 14\frac{1}{4} (or 1040\frac{10}{40}) volume with pure water yields 1940=0.475\frac{19}{40} = 0.475 of the total solution as water.

Adım Adım Çözüm

1
Track water content after the initial replacement.
Water fraction becomes 310\frac{3}{10} of the original volume.
Let the original total volume be VV. Initially, water volume is 38V\frac{3}{8}V. Removing 15\frac{1}{5} of the solution leaves 45\frac{4}{5} of the original solution, so the water volume becomes 45×38V=310V\frac{4}{5} \times \frac{3}{8}V = \frac{3}{10}V. Replacing the removed volume with pure ethanol brings total volume back to VV, with water occupying 310V\frac{3}{10}V.
2
Track water content after evaporation.
Water volume becomes 940V\frac{9}{40}V and total solution volume becomes 34V\frac{3}{4}V.
Evaporating 14\frac{1}{4} of the solution leaves 34\frac{3}{4} of the mixture intact. The remaining water volume is 34×310V=940V\frac{3}{4} \times \frac{3}{10}V = \frac{9}{40}V.
3
Calculate the final water fraction after refilling with pure water.
Final water volume is 1940V=0.475V\frac{19}{40}V = 0.475V.
To restore the total volume from 34V\frac{3}{4}V back to VV, an amount equal to V34V=14VV - \frac{3}{4}V = \frac{1}{4}V of pure water is added. Adding this to the existing water gives 940V+14V=940V+1040V=1940V\frac{9}{40}V + \frac{1}{4}V = \frac{9}{40}V + \frac{10}{40}V = \frac{19}{40}V. Dividing by total volume VV yields 1940=0.475\frac{19}{40} = 0.475.

Anahtar Kavram

Sequential fractional reduction and component tracking
Tahmini Süre:2m 30s
Soru 12Soru

If aa and bb are positive rational numbers such that a<b<1a < b < 1, which of the following expressions must be strictly greater than 11? Select all that apply.

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Cevap: ba\frac{b}{a}; a+1b\frac{a+1}{b}; b+1a+1\frac{b+1}{a+1}

Cevap

The expressions that must be strictly greater than 1 are the ratio of b to a, the fraction (a + 1) over b, and the fraction (b + 1) over (a + 1).
The correct options are those involving ratios where the numerator is demonstrably greater than the denominator. The ratio of b to a compares two positive numbers where b is larger, giving a quotient greater than 1. The fraction with numerator (a + 1) has a value over 1 while denominator b is under 1, ensuring the quotient exceeds 1. The fraction comparing (b + 1) to (a + 1) has a larger numerator because adding 1 preserves the inequality b > a.

Adım Adım Çözüm

1
Analyze the ratio of b to a
Since b>a>0b > a > 0, ba>1\frac{b}{a} > 1 is always true.
Dividing any positive number by a smaller positive number results in a value greater than 1.
2
Analyze the fraction (a + 1) over b
Since a>0a > 0, a+1>1a + 1 > 1. Since b<1b < 1, a+1>ba + 1 > b, which implies a+1b>1\frac{a+1}{b} > 1.
The numerator is greater than 1 and the denominator is less than 1, so the fraction exceeds 1.
3
Test counterexamples for the fraction a over b squared
For a=18a = \frac{1}{8} and b=12b = \frac{1}{2}, ab2=1/81/4=121\frac{a}{b^2} = \frac{1/8}{1/4} = \frac{1}{2} \le 1.
The expression is not guaranteed to be greater than 1 for all valid values of a and b.
4
Analyze the fraction (b + 1) over (a + 1)
Since b>ab > a, adding 1 to both quantities yields b+1>a+1>0b + 1 > a + 1 > 0, so b+1a+1>1\frac{b+1}{a+1} > 1.
Adding the same positive quantity to two numbers maintains their relative order.
5
Analyze the average fraction (a + b) over 2b
Since a<ba < b, a+b<2ba + b < 2b, meaning a+b2b<1\frac{a+b}{2b} < 1.
The numerator is the sum of a and b, which is strictly less than twice b.

Anahtar Kavram

Properties of Rational Number Inequalities and Fraction Comparison
Tahmini Süre:1m 30s
Soru 13Soru

A community library received a donation of 120120 new books. On Monday, 38\frac{3}{8} of the donated books were cataloged. On Tuesday, 13\frac{1}{3} of the remaining uncataloged books were cataloged. How many of the donated books remain to be cataloged?

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Cevap: 50

Cevap

50 books remain to be cataloged.
First, find the number of books cataloged on Monday: 3/8 of 120 is 45 books. Subtracting 45 from 120 leaves 75 books uncataloged. On Tuesday, 1/3 of those remaining 75 books were cataloged, which is 25 books. Subtracting 25 from 75 gives 50 books remaining to be cataloged.

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1
Calculate the number of books cataloged on Monday.
45 books
Multiply the initial total of 120 books by the fraction cataloged on Monday, which is 3/8.
2
Calculate the uncataloged books remaining after Monday.
75 books
Subtract the 45 cataloged books from the initial 120 books.
3
Calculate the number of books cataloged on Tuesday.
25 books
Multiply the remaining 75 books by the fraction cataloged on Tuesday, which is 1/3.
4
Calculate the final number of uncataloged books.
50 books
Subtract the 25 books cataloged on Tuesday from the 75 uncataloged books remaining after Monday.

Anahtar Kavram

Fraction of a Remaining Quantity
Tahmini Süre:50s
Soru 14Soru

A university research lab receives a multi-year grant. In the first quarter, the lab spends 27\frac{2}{7} of the total grant on laboratory equipment. In the second quarter, the lab spends 35\frac{3}{5} of the remaining funds on research staff salaries. At the beginning of the third quarter, the lab receives a supplementary addition equal to 14\frac{1}{4} of the funds remaining at the end of the second quarter. If the total amount of money in the grant immediately following the third-quarter addition is $45,000\$45,000, what was the initial dollar amount of the research grant?

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Cevap: $126,000

Cevap

$126,000
The correct answer of 126,000isfoundbytrackingthefractionoftheinitialgrant126,000 is found by tracking the fraction of the initial grant G remainingaftereachstep.Spending remaining after each step. Spending \frac{2}{7}leaves leaves \frac{5}{7}G .Spending. Spending \frac{3}{5}ofthatremainderleaves of that remainder leaves \frac{2}{5} \times \frac{5}{7}G = \frac{2}{7}G .Adding. Adding \frac{1}{4}of of \frac{2}{7}G increasesthebalanceby increases the balance by \frac{1}{14}G ,resultinginafinaltotalof, resulting in a final total of \frac{2}{7}G + \frac{1}{14}G = \frac{5}{14}G .Setting. Setting \frac{5}{14}G = 45,000 yields yields G = 126,000$.

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1
Determine the remaining fraction after the first quarter.
Fraction remaining = 127=571 - \frac{2}{7} = \frac{5}{7} of the initial grant GG.
The lab spent 27\frac{2}{7} of the total grant.
2
Calculate the remaining fraction after the second quarter.
Fraction remaining = (135)×57G=25×57G=27G\left(1 - \frac{3}{5}\right) \times \frac{5}{7}G = \frac{2}{5} \times \frac{5}{7}G = \frac{2}{7}G.
The lab spent 35\frac{3}{5} of the remaining funds, leaving 25\frac{2}{5} of those funds.
3
Account for the third-quarter supplementary addition.
Final fraction = 27G+14(27G)=27G+114G=414G+114G=514G\frac{2}{7}G + \frac{1}{4}\left(\frac{2}{7}G\right) = \frac{2}{7}G + \frac{1}{14}G = \frac{4}{14}G + \frac{1}{14}G = \frac{5}{14}G.
An additional 14\frac{1}{4} of the second-quarter remaining funds was added to the grant.
4
Solve for the initial grant amount GG.
514G=45,000    G=45,000×145=9,000×14=126,000\frac{5}{14}G = 45,000 \implies G = 45,000 \times \frac{14}{5} = 9,000 \times 14 = 126,000.
The final remaining balance of $45,000\$45,000 corresponds to 514\frac{5}{14} of the original grant.

Anahtar Kavram

Multi-step sequential fraction operations and base tracking in word problems
Soru 15Soru

An industrial chemical reservoir is emptied by three pumps, P1P_1, P2P_2, and P3P_3, operating independently at different constant rates. Working alone, P1P_1 can empty the full reservoir in 66 hours, P2P_2 can empty it in 88 hours, and P3P_3 can empty it in 1212 hours. Initially, the reservoir is completely full. First, P1P_1 and P2P_2 work together for 22 hours. Then P1P_1 is turned off, and P3P_3 is turned on to work alongside P2P_2. Additionally, while P2P_2 and P3P_3 are working together, a defect causes liquid to leak out of the bottom of the reservoir at a constant rate equal to 16\frac{1}{6} of the combined emptying rate of P2P_2 and P3P_3. How many additional hours will it take to completely empty the remaining liquid from the reservoir?

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Cevap: 127\frac{12}{7} hours

Cevap

127\frac{12}{7} hours
The option stating '127\frac{12}{7} hours' is correct because during the first 2 hours, P1P_1 and P2P_2 empty 712\frac{7}{12} of the reservoir, leaving 512\frac{5}{12} remaining. Then, P2P_2 and P3P_3 have a combined rate of 524\frac{5}{24}, and the defect adds an extra 5144\frac{5}{144} per hour, giving a total emptying rate of 35144\frac{35}{144} reservoirs per hour. Dividing 512\frac{5}{12} by 35144\frac{35}{144} yields 127\frac{12}{7} hours.

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1
Calculate the combined emptying rate of P1P_1 and P2P_2 and determine the fraction emptied in the first 22 hours.
Rate of P1=16P_1 = \frac{1}{6} reservoir/hr, Rate of P2=18P_2 = \frac{1}{8} reservoir/hr. Combined rate = \frac{1}{6} + \frac{1}{8} = \frac{7}{24} reservoir/hr. In 22 hours, amount emptied = 2×724=7122 \times \frac{7}{24} = \frac{7}{12} of the reservoir.
Determines how much work was completed during the initial stage.
2
Find the remaining fraction of liquid in the reservoir.
Remaining fraction = 1712=5121 - \frac{7}{12} = \frac{5}{12} of the reservoir.
Establishes the remaining volume that must be emptied in the second stage.
3
Calculate the combined rate of P2P_2, P3P_3, and the defect rate.
Combined rate of P2P_2 and P3=18+112=524P_3 = \frac{1}{8} + \frac{1}{12} = \frac{5}{24} reservoir/hr. Defect rate = \frac{1}{6} \times \frac{5}{24} = \frac{5}{144} reservoir/hr. Total emptying rate = \frac{5}{24} + \frac{5}{144} = \frac{30 + 5}{144} = \frac{35}{144} reservoir/hr.
Combines all simultaneous emptying processes during the second stage.
4
Divide the remaining fraction by the total emptying rate to find the additional time needed.
Time = \frac{5/12}{35/144} = \frac{5}{12} \times \frac{144}{35} = \frac{5}{35} \times \frac{144}{12} = \frac{1}{7} \times 12 = \frac{12}{7} hours.
Applies the rate formula Time=WorkRate\text{Time} = \frac{\text{Work}}{\text{Rate}}.

Anahtar Kavram

Compound Fraction Work Rates and Rational Operations
Soru 16Soru

Let aa and bb be rational numbers such that 1<a<0<b<1-1 < a < 0 < b < 1. Which of the following expressions MUST be strictly greater than 11? Select all such expressions.

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Cevap: bab\frac{b - a}{b}; 1+b1+a\frac{1 + b}{1 + a}

Cevap

The expressions bab\frac{b - a}{b} and 1+b1+a\frac{1 + b}{1 + a} MUST be strictly greater than 1.
The expression representing the difference (ba)(b - a) divided by bb simplifies to 1+ab1 + \frac{-a}{b}. Because a-a and bb are both positive, this term is strictly greater than 1. Similarly, the expression 1+b1+a\frac{1 + b}{1 + a} divides a numerator greater than 1 by a positive denominator less than 1, which always yields a value strictly greater than 1.

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1
Analyze the expression bab\frac{b - a}{b} by splitting the fraction.
bab=bbab=1ab\frac{b - a}{b} = \frac{b}{b} - \frac{a}{b} = 1 - \frac{a}{b}.
Since a<0a < 0 and b>0b > 0, the quotient ab\frac{a}{b} is strictly negative. Subtracting a negative number from 1 is equivalent to adding a positive number, so 1ab>11 - \frac{a}{b} > 1.
2
Analyze the expression 1+b1+a\frac{1 + b}{1 + a} by establishing bounds for the numerator and denominator.
Since b>0b > 0, 1+b>11 + b > 1. Since 1<a<0-1 < a < 0, adding 1 yields 0<1+a<10 < 1 + a < 1.
Dividing any real number greater than 1 by a positive real number less than 1 produces a value strictly greater than 1.
3
Evaluate the remaining options with counterexamples or algebraic bounds to verify they are not guaranteed to be greater than 1.
The expression a+bb=1+ab<1\frac{a + b}{b} = 1 + \frac{a}{b} < 1; the expression ba1a<1\frac{b - a}{1 - a} < 1 because b<1    ba<1ab < 1 \implies b - a < 1 - a; and 1ba\frac{1}{b - a} can be less than 1 when ba>1b - a > 1 (e.g., b=0.8,a=0.5    ba=1.3b = 0.8, a = -0.5 \implies b - a = 1.3).
Demonstrating that an expression is less than 1 or can be less than 1 eliminates it from being strictly greater than 1 for all valid rational numbers aa and bb.

Anahtar Kavram

Properties and Inequalities of Rational Numbers
Soru 17Soru

An investment fund allocates its total portfolio assets among three asset classes: stocks, bonds, and real estate. Initially, 512\frac{5}{12} of the total portfolio is invested in stocks and 13\frac{1}{3} of the total portfolio is invested in bonds, with the remaining fraction invested in real estate. If 25\frac{2}{5} of the stock portfolio and 14\frac{1}{4} of the bond portfolio are subsequently liquidated, what fraction of the fund's remaining total portfolio is invested in real estate?

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Cevap: 13\frac{1}{3}

Cevap

The fraction of the fund's remaining total portfolio invested in real estate is 13\frac{1}{3}.
Let the original total portfolio be TT. Initially, stocks are 512T\frac{5}{12}T, bonds are 412T\frac{4}{12}T, and real estate is 1912T=312T1 - \frac{9}{12}T = \frac{3}{12}T. After liquidating 25\frac{2}{5} of stocks and 14\frac{1}{4} of bonds, the remaining stock value is 35×512T=312T\frac{3}{5} \times \frac{5}{12}T = \frac{3}{12}T and the remaining bond value is 34×412T=312T\frac{3}{4} \times \frac{4}{12}T = \frac{3}{12}T. Real estate remains 312T\frac{3}{12}T. The new total portfolio is 312T+312T+312T=912T=34T\frac{3}{12}T + \frac{3}{12}T + \frac{3}{12}T = \frac{9}{12}T = \frac{3}{4}T. Therefore, real estate represents 3/12T9/12T=39=13\frac{3/12 T}{9/12 T} = \frac{3}{9} = \frac{1}{3} of the remaining total portfolio.

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1
Determine the initial fraction invested in real estate.
Real estate accounts for 1(512+13)=1912=312=141 - \left(\frac{5}{12} + \frac{1}{3}\right) = 1 - \frac{9}{12} = \frac{3}{12} = \frac{1}{4} of the original total portfolio.
The sum of all three asset fractions must equal 1.
2
Calculate the remaining fractions for stocks and bonds after liquidation.
Remaining stocks = (125)×512=35×512=312\left(1 - \frac{2}{5}\right) \times \frac{5}{12} = \frac{3}{5} \times \frac{5}{12} = \frac{3}{12}. Remaining bonds = (114)×13=34×412=312\left(1 - \frac{1}{4}\right) \times \frac{1}{3} = \frac{3}{4} \times \frac{4}{12} = \frac{3}{12}.
Multiplying the unliquidated fraction by each asset's initial fraction gives its remaining fraction relative to the original total.
3
Calculate the total remaining portfolio fraction.
Total remaining portfolio = 312 (stocks)+312 (bonds)+312 (real estate)=912=34\frac{3}{12} \text{ (stocks)} + \frac{3}{12} \text{ (bonds)} + \frac{3}{12} \text{ (real estate)} = \frac{9}{12} = \frac{3}{4} of the original total portfolio.
Sum the remaining portions of all three asset categories.
4
Compute the ratio of real estate to the remaining total portfolio.
\frac{\text{Real Estate}}{\text{Remaining Total}} = \frac{\frac{1}{4}}{\frac{3}{4}} = \frac{1}{3}.
The question asks for the fraction relative to the new reduced total portfolio.

Anahtar Kavram

Sequential Fraction Allocation and Reduced Base Ratios
Tahmini Süre:1m 30s
Soru 18Soru
Let aa, bb, and cc be positive integers, and define three rational numbers xx, yy, and zz as follows:
x=aa+b,y=bb+c,andz=cc+ax = \frac{a}{a+b}, \quad y = \frac{b}{b+c}, \quad \text{and} \quad z = \frac{c}{c+a}
Which of the following statements MUST be true for all such positive integers aa, bb, and cc? Select all that apply.

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Cevap: The sum x+y+zx + y + z satisfies the inequality 1<x+y+z<21 < x + y + z < 2.; The product (1x)(1y)(1z)(1 - x)(1 - y)(1 - z) is identically equal to xyzxyz.; The product xyzxyz cannot exceed 18\frac{1}{8}.

Cevap

The statements asserting that 1<x+y+z<21 < x + y + z < 2, that (1x)(1y)(1z)=xyz(1 - x)(1 - y)(1 - z) = xyz, and that xyz18xyz \le \frac{1}{8} are all true.
The statement bounding the sum between 1 and 2 is correct because adjusting denominators to a common sum a+b+ca+b+c reveals that the sum is strictly greater than 1 and strictly less than 2. The identity statement is correct because subtracting each fraction from 1 shifts the numerators cyclically without changing the overall product. The statement placing an upper bound of 18\frac{1}{8} on the product is correct by applying the AM-GM inequality to each denominator term.

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1
Establish strict bounds on the sum x+y+zx + y + z.
Since a,b,c>0a, b, c > 0, we have aa+b>aa+b+c\frac{a}{a+b} > \frac{a}{a+b+c}. Summing all three terms gives x+y+z>a+b+ca+b+c=1x + y + z > \frac{a+b+c}{a+b+c} = 1. To find the upper bound, rewrite aa+b<a+ca+b+c\frac{a}{a+b} < \frac{a+c}{a+b+c}. Summing all three terms gives x+y+z<(a+c)+(a+b)+(b+c)a+b+c=2x + y + z < \frac{(a+c)+(a+b)+(b+c)}{a+b+c} = 2. Thus, 1<x+y+z<21 < x + y + z < 2.
This proves that the sum of the three fractions must always lie strictly between 1 and 2.
2
Compute the product (1x)(1y)(1z)(1-x)(1-y)(1-z) algebraically.
1x=1aa+b=ba+b1 - x = 1 - \frac{a}{a+b} = \frac{b}{a+b}, 1y=cb+c1 - y = \frac{c}{b+c}, and 1z=ac+a1 - z = \frac{a}{c+a}. The product is bca(a+b)(b+c)(c+a)=abc(a+b)(b+c)(c+a)=xyz\frac{b \cdot c \cdot a}{(a+b)(b+c)(c+a)} = \frac{abc}{(a+b)(b+c)(c+a)} = xyz.
This proves the structural algebraic identity between (1x)(1y)(1z)(1-x)(1-y)(1-z) and xyzxyz.
3
Apply the AM-GM inequality to find the upper bound of xyzxyz.
Since a+b2aba+b \ge 2\sqrt{ab}, b+c2bcb+c \ge 2\sqrt{bc}, and c+a2cac+a \ge 2\sqrt{ca}, their product satisfies (a+b)(b+c)(c+a)8a2b2c2=8abc(a+b)(b+c)(c+a) \ge 8\sqrt{a^2b^2c^2} = 8abc. Taking the reciprocal gives xyz=abc(a+b)(b+c)(c+a)abc8abc=18xyz = \frac{abc}{(a+b)(b+c)(c+a)} \le \frac{abc}{8abc} = \frac{1}{8}.
This confirms that xyzxyz has a maximum possible value of 18\frac{1}{8} (achieved when a=b=ca=b=c).
4
Test counterexamples for the remaining statements.
Since 1<x+y+z<21 < x + y + z < 2, no integer value is possible, ruling out integer sums. Additionally, substituting a=1,b=2,c=1a=1, b=2, c=1 gives x=13,y=23,z=12x=\frac{1}{3}, y=\frac{2}{3}, z=\frac{1}{2}, whose sum is 32\frac{3}{2} despite x,y,zx, y, z not being equal to 12\frac{1}{2}.
This disproves the statements claiming the sum can be an integer or that a sum of 32\frac{3}{2} requires all three fractions to be equal.

Anahtar Kavram

Bounding and algebraic properties of cyclic rational fractions
Tahmini Süre:3m 0s
Soru 19Soru

An asset management firm divides its total portfolio into three distinct funds: Fund X, Fund Y, and Fund Z. Initially, 13\frac{1}{3} of the total portfolio value is in Fund X, and 25\frac{2}{5} is in Fund Y, with the remaining fraction in Fund Z. Over the course of one year, the value of Fund X increases by 15\frac{1}{5}, the value of Fund Y decreases by 14\frac{1}{4}, and the value of Fund Z increases by 12\frac{1}{2}. At the end of the year, what fraction of the portfolio's total value is contained in Fund Z?

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Cevap: 411\frac{4}{11}

Cevap

The fraction of the portfolio's total final value contained in Fund Z is 411\frac{4}{11}.
Fund Z grows to 25\frac{2}{5} of the original portfolio value, while the overall portfolio value increases to 1110\frac{11}{10} of the original total. Comparing Fund Z's final value to the new total yields 2/511/10=411\frac{2/5}{11/10} = \frac{4}{11}.

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1
Calculate the initial fraction of the total portfolio allocated to Fund Z.
The initial allocation for Fund Z is 1(13+25)=11115=4151 - \left(\frac{1}{3} + \frac{2}{5}\right) = 1 - \frac{11}{15} = \frac{4}{15}.
The sum of all initial fund allocations must equal 1.
2
Determine the final value of each fund relative to the initial total portfolio value VV.
Fund X: 13V×(1+15)=25V\frac{1}{3}V \times \left(1 + \frac{1}{5}\right) = \frac{2}{5}V. Fund Y: 25V×(114)=310V\frac{2}{5}V \times \left(1 - \frac{1}{4}\right) = \frac{3}{10}V. Fund Z: 415V×(1+12)=25V\frac{4}{15}V \times \left(1 + \frac{1}{2}\right) = \frac{2}{5}V.
Multiply each initial fund share by its respective growth or reduction factor.
3
Calculate the new total portfolio value relative to the initial value VV.
Total final value = 25V+310V+25V=410V+310V+410V=1110V\frac{2}{5}V + \frac{3}{10}V + \frac{2}{5}V = \frac{4}{10}V + \frac{3}{10}V + \frac{4}{10}V = \frac{11}{10}V.
Sum the final values of all three individual funds.
4
Compute the final fraction of the portfolio contained in Fund Z.
Fraction = 25V1110V=25×1011=411\frac{\frac{2}{5}V}{\frac{11}{10}V} = \frac{2}{5} \times \frac{10}{11} = \frac{4}{11}.
Divide the final value of Fund Z by the new total portfolio value.

Anahtar Kavram

Rational number operations and shifting base values in multi-step fraction problems
Tahmini Süre:2m 0s
Soru 20Soru

A laboratory container holds a solution composed solely of alcohol, acid, and water. Initially, alcohol accounts for 38\frac{3}{8} of the solution's total volume, and acid accounts for 14\frac{1}{4} of the total volume. In a two-step process, a chemist first removes 13\frac{1}{3} of the alcohol present and 12\frac{1}{2} of the acid present, with no water removed. Next, the chemist adds pure water until water accounts for 35\frac{3}{5} of the solution's new total volume. What fraction of the final solution's total volume is alcohol?

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Cevap: 415\frac{4}{15}

Cevap

The fraction of the final solution's total volume that is alcohol is 415\frac{4}{15}.
The correct fraction 415\frac{4}{15} is derived by calculating the remaining alcohol volume as 14\frac{1}{4} of the initial total volume VV, and determining the final total volume Vfinal=1516VV_{\text{final}} = \frac{15}{16}V using the constant non-water volume of 38V\frac{3}{8}V. Dividing 14V\frac{1}{4}V by 1516V\frac{15}{16}V yields 415\frac{4}{15}.

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1
Determine initial volume fractions for all three components.
Let VV be the initial total volume. Alcohol is 38V\frac{3}{8}V, acid is 14V=28V\frac{1}{4}V = \frac{2}{8}V, and water is 1(38+28)=38V1 - (\frac{3}{8} + \frac{2}{8}) = \frac{3}{8}V.
Establishing the initial baseline volumes allows accurate tracking through the multi-step changes.
2
Calculate component volumes after the removal step.
Remaining alcohol = 38V×(113)=14V\frac{3}{8}V \times (1 - \frac{1}{3}) = \frac{1}{4}V. Remaining acid = 14V×(112)=18V\frac{1}{4}V \times (1 - \frac{1}{2}) = \frac{1}{8}V. Water remains 38V\frac{3}{8}V.
Removing specified fractions of individual components changes their absolute volumes.
3
Calculate non-water volume and final total volume after water is added.
Total non-water volume = 14V+18V=38V\frac{1}{4}V + \frac{1}{8}V = \frac{3}{8}V. Since water becomes 35\frac{3}{5} of the final volume VfinalV_{\text{final}}, non-water is 135=251 - \frac{3}{5} = \frac{2}{5} of VfinalV_{\text{final}}. Thus, 25Vfinal=38V    Vfinal=52×38V=1516V\frac{2}{5} V_{\text{final}} = \frac{3}{8}V \implies V_{\text{final}} = \frac{5}{2} \times \frac{3}{8}V = \frac{15}{16}V.
Adding only water keeps the non-water volume constant, providing a fixed reference point to find the new total volume.
4
Compute the final fraction of alcohol in the solution.
\text{Alcohol Fraction} = \frac{\text{Alcohol Volume}}{V_{\text{final}}} = \frac{\frac{1}{4}V}{\frac{15}{16}V} = \frac{1}{4} \times \frac{16}{15} = \frac{4}{15}.
The required quantity is the part-to-whole ratio of remaining alcohol to the final total volume.

Anahtar Kavram

Multi-step fraction operations involving component-wise removals and fixed non-water volumes in liquid mixtures.
Tahmini Süre:2m 30s
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