Word Problems and Applied Math

188 soru

Soru 81Soru

A merchant combines 1010 kilograms of Brand A tea costing $20\$20 per kilogram with 3030 kilograms of Brand B tea costing $40\$40 per kilogram. What is the average cost per kilogram of the combined mixture?

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Cevap: $35\$35

Cevap

The average cost per kilogram of the combined tea mixture is $35\$35.
The correct option of $35\$35 properly weights each unit price by its respective quantity. Brand A contributes 10×20=$20010 \times 20 = \$200 and Brand B contributes 30×40=$120030 \times 40 = \$1200, giving a combined total cost of $1400\$1400 for 4040 kg. Dividing $1400\$1400 by 4040 yields $35\$35 per kilogram.

Adım Adım Çözüm

1
Calculate the total cost of Brand A tea
10 kg×$20/kg=$20010 \text{ kg} \times \$20/\text{kg} = \$200
To find the overall weighted cost, we first determine the total dollar amount spent on Brand A.
2
Calculate the total cost of Brand B tea
30 kg×$40/kg=$120030 \text{ kg} \times \$40/\text{kg} = \$1200
Next, we calculate the total dollar amount spent on Brand B.
3
Find total combined cost and total combined weight
\text{Total cost} = \$200 + \$1200 = \$1400; \text{Total weight} = 10 + 30 = 40 \text{ kg}
Sum the total cost of both components and their combined weights.
4
Divide total combined cost by total combined weight
\text{Weighted Average Cost} = \frac{\$1400}{40 \text{ kg}} = \$35/\text{kg}
The weighted average formula is Total Cost divided by Total Quantity.

Anahtar Kavram

Weighted Average in Applied Contexts
Tahmini Süre:1m 0s
Soru 82Soru

A commercial bakery prepares a specialty grain blend using Organic Wheat, Spelt, and Rye flour. Initially, the ratio of Organic Wheat to Spelt to Rye flour in the batch is 4:3:24 : 3 : 2 by weight. To meet specific recipe requirements, 3030 kilograms of Organic Wheat and 1515 kilograms of Spelt are added to the batch, while 1010 kilograms of Rye are removed. After these adjustments, the ratio of Organic Wheat to Rye flour in the batch becomes 3:13 : 1. What was the total weight, in kilograms, of the initial batch of flour before any adjustments were made?

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Cevap: 270

Cevap

270 kilograms
By representing the initial amounts of Organic Wheat, Spelt, and Rye as 4x4x, 3x3x, and 2x2x kilograms respectively, the initial total weight is 9x9x kilograms. Following the adjustments, the new amount of Wheat is 4x+304x + 30 kg and the new amount of Rye is 2x102x - 10 kg. Equating their ratio to 3:13 : 1 gives 4x+302x10=31\frac{4x + 30}{2x - 10} = \frac{3}{1}. Solving for xx gives 4x+30=6x304x + 30 = 6x - 30, leading to 2x=602x = 60 or x=30x = 30. Therefore, the initial total weight of the flour batch was 9×30=2709 \times 30 = 270 kilograms.

Adım Adım Çözüm

1
Define initial quantities using a common multiplier xx.
Organic Wheat =4x= 4x, Spelt =3x= 3x, Rye =2x= 2x. Initial total weight =4x+3x+2x=9x= 4x + 3x + 2x = 9x.
The initial ratio 4:3:24 : 3 : 2 specifies the relative proportions of the three components in the batch.
2
Express the updated amounts after additions and removals.
New Organic Wheat =4x+30= 4x + 30, New Spelt =3x+15= 3x + 15, New Rye =2x10= 2x - 10.
Incorporating the specified additions (+30+30 kg Wheat, +15+15 kg Spelt) and removal (10-10 kg Rye).
3
Set up an equation using the new ratio of Organic Wheat to Rye (3:13 : 1).
4x+302x10=31\frac{4x + 30}{2x - 10} = \frac{3}{1}
The problem states that the updated ratio of Wheat to Rye is 3:13 : 1.
4
Solve for the multiplier xx.
4x+30=3(2x10)    4x+30=6x30    2x=60    x=304x + 30 = 3(2x - 10) \implies 4x + 30 = 6x - 30 \implies 2x = 60 \implies x = 30.
Cross-multiplying and solving the linear equation yields x=30x = 30.
5
Calculate the total weight of the initial batch.
Initial total =9x=9×30=270= 9x = 9 \times 30 = 270 kilograms.
Substituting x=30x = 30 back into the initial total expression 9x9x gives the required initial batch mass.

Anahtar Kavram

Ratio Modification and Multi-Part Proportions
Tahmini Süre:2m 0s
Soru 83Soru

At a technology company, a team of 6060 software engineers works on product development. Of these engineers, 3535 work on the mobile application, 2828 work on the web platform, and 1010 work on neither project. How many engineers work on both the mobile application and the web platform?

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Cevap: 1313

Cevap

13 engineers work on both the mobile application and the web platform.
According to the fundamental principle of overlapping sets for two groups, the total number of individuals in the universe is equal to the number of individuals in Group A plus the number in Group B, minus those counted in both groups (to prevent double counting), plus those in neither group: Total=Set A+Set BBoth+Neither\text{Total} = \text{Set A} + \text{Set B} - \text{Both} + \text{Neither}. Substituting the given values gives 60=35+28Both+1060 = 35 + 28 - \text{Both} + 10. Simplifying the right side yields 60=73Both60 = 73 - \text{Both}, so Both=13\text{Both} = 13. Thus, the value 1313 is correct.

Adım Adım Çözüm

1
Identify the given set values and formula
Total=60\text{Total} = 60, Mobile=35\text{Mobile} = 35, Web=28\text{Web} = 28, Neither=10\text{Neither} = 10
Define all components of the standard two-set overlapping formula: Total=Set A+Set BBoth+Neither\text{Total} = \text{Set A} + \text{Set B} - \text{Both} + \text{Neither}.
2
Substitute the values into the overlapping sets formula
60=35+28Both+1060 = 35 + 28 - \text{Both} + 10
Set up the linear equation to solve for the unknown intersection (Both).
3
Simplify and solve for Both
60=73Both    Both=7360=1360 = 73 - \text{Both} \implies \text{Both} = 73 - 60 = 13
Combine like terms (35+28+10=7335 + 28 + 10 = 73) and isolate the variable to find the number of engineers in both groups.

Anahtar Kavram

Two-Set Overlapping Venn Diagram Principle
Tahmini Süre:1m 0s
Soru 84Soru

A boutique perfumery blends three essential oils—Jasmine, Sandalwood, and Bergamot—in an initial volume ratio of 4:3:24 : 3 : 2, respectively. To modify the fragrance profile, the perfumer adds 20 milliliters20\text{ milliliters} of Sandalwood and 40 milliliters40\text{ milliliters} of Bergamot to the mixture, leaving the amount of Jasmine unchanged. If the resulting volume ratio of Sandalwood to Bergamot is 5:65 : 6, what was the total initial volume, in milliliters, of the fragrance batch?

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Cevap: 90

Cevap

The total initial volume of the fragrance batch was 90 milliliters.
By representing the initial amounts of Jasmine, Sandalwood, and Bergamot as 4x4x, 3x3x, and 2x2x respectively, the total initial volume is 9x9x. Setting up the proportion 3x+202x+40=56\frac{3x + 20}{2x + 40} = \frac{5}{6} yields x=10x = 10. Substituting x=10x = 10 into 9x9x gives the initial volume of 90 milliliters.

Adım Adım Çözüm

1
Define variables for the initial quantities using the given ratio.
Jasmine volume = 4x4x, Sandalwood volume = 3x3x, Bergamot volume = 2x2x, where xx is a positive multiplier. Total initial volume = 4x+3x+2x=9x4x + 3x + 2x = 9x.
Representing ratio parts algebraically allows setting up equations for the modified amounts.
2
Formulate an equation based on the new ratio after adding essential oils.
New Sandalwood volume = 3x+203x + 20, New Bergamot volume = 2x+402x + 40. Equating their ratio to 5:65 : 6 gives 3x+202x+40=56\frac{3x + 20}{2x + 40} = \frac{5}{6}.
The problem specifies the new relationship between Sandalwood and Bergamot.
3
Solve the proportion for xx.
Cross-multiplying gives 6(3x+20)=5(2x+40)    18x+120=10x+200    8x=80    x=106(3x + 20) = 5(2x + 40) \implies 18x + 120 = 10x + 200 \implies 8x = 80 \implies x = 10.
Finding the multiplier xx allows us to calculate the exact initial quantities.
4
Compute the total initial volume.
Total initial volume = 9x=9×10=909x = 9 \times 10 = 90 milliliters.
The question asks for the total initial volume of the batch.

Anahtar Kavram

Solving multi-step ratio problems involving additions to individual components by establishing an algebraic multiplier.
Soru 85Soru

A pharmaceutical laboratory prepares a liquid vaccine solution by blending three ingredients: Active Compound X, Active Compound Y, and Distilled Water in the volume ratio of 3:4:83 : 4 : 8, respectively. To meet updated formulation guidelines, a chemist adds 1212 liters of Active Compound Y and 3636 liters of Distilled Water to the solution, leaving the quantity of Active Compound X unchanged. If the new ratio of Active Compound X to Distilled Water in the resulting solution is 1:41 : 4, what was the total volume, in liters, of the solution before any ingredients were added?

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Cevap: 135

Cevap

The total volume of the solution before any ingredients were added was 135 liters.
Representing the initial volumes of Active Compound X, Active Compound Y, and Distilled Water as 3x3x, 4x4x, and 8x8x, the initial total volume is 15x15x liters. After adding 3636 liters of Distilled Water while keeping Compound X at 3x3x liters, the ratio of X to Water becomes 3x8x+36=14\frac{3x}{8x + 36} = \frac{1}{4}. Solving 12x=8x+3612x = 8x + 36 gives 4x=364x = 36, so x=9x = 9. Multiplying 1515 by 99 gives the initial total volume of 135135 liters.

Adım Adım Çözüm

1
Define the initial component quantities using a common ratio multiplier
The initial volumes of Compound X, Compound Y, and Distilled Water are 3x3x, 4x4x, and 8x8x liters, giving an initial total volume of 15x15x liters.
A ratio of 3:4:83 : 4 : 8 means the actual quantities are integer multiples of a common constant xx.
2
Set up the ratio equation reflecting the additions
The equation comparing the unchanged Compound X to the updated volume of Distilled Water is 3x8x+36=14\frac{3x}{8x + 36} = \frac{1}{4}.
No Compound X was added, so its volume stays 3x3x, whereas 3636 liters were added to the initial 8x8x liters of Distilled Water.
3
Solve the algebraic equation for the multiplier xx
4(3x)=1(8x+36)    12x=8x+36    4x=36    x=94(3x) = 1(8x + 36) \implies 12x = 8x + 36 \implies 4x = 36 \implies x = 9.
Cross-multiplying isolates the terms with xx and allows solving for the multiplier.
4
Calculate the target initial total volume
15×9=13515 \times 9 = 135 liters.
Substituting x=9x = 9 into the initial total volume expression 15x15x yields the final answer.

Anahtar Kavram

Solving multi-step ratio word problems by setting up unknown multiplier equations based on partial component alterations
Soru 86Soru

A container initially holds 100100 liters of an acid solution that is 40%40\% acid by volume. First, xx liters of the solution are drained and replaced with an equal volume of pure water. After the mixture is thoroughly stirred, xx liters of the new solution are drained and replaced with an equal volume of pure acid. If the final solution is 45.6%45.6\% acid by volume, what is the value of xx?

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Cevap: 20

Cevap

The value of xx is 2020 liters.
The solution requires tracking the amount of pure acid through two distinct replacement operations. Initially, there are 4040 liters of acid in 100100 liters of solution. Draining xx liters removes 0.4x0.4x liters of acid, leaving (400.4x)(40 - 0.4x) liters of acid after adding xx liters of pure water. In the second step, draining xx liters removes a fraction x100\frac{x}{100} of the remaining acid, leaving (400.4x)(1x100)(40 - 0.4x)(1 - \frac{x}{100}) liters of acid. Adding xx liters of pure acid yields a total acid volume of (400.4x)(1x100)+x=45.6(40 - 0.4x)(1 - \frac{x}{100}) + x = 45.6 liters. Expanding and solving the resulting quadratic equation x2+50x1400=0x^2 + 50x - 1400 = 0 gives x=20x = 20 (since x>0x > 0).

Adım Adım Çözüm

1
Determine initial volume of solute (pure acid).
Initial acid volume = 40%×100=4040\% \times 100 = 40 liters.
Establishing the starting amount of pure acid in the 100100-liter container.
2
Model the acid amount after the first replacement (with water).
Acid volume after first replacement = 40(1x100)40\left(1 - \frac{x}{100}\right) liters.
Draining xx liters removes x100\frac{x}{100} of the total acid, and adding water adds zero acid.
3
Model the acid amount after the second replacement (with pure acid).
Final acid volume = 40(1x100)(1x100)+x40\left(1 - \frac{x}{100}\right)\left(1 - \frac{x}{100}\right) + x liters.
Draining xx liters of the new solution removes x100\frac{x}{100} of its acid, and replacing with pure acid adds xx liters of acid.
4
Set up and solve the quadratic equation given final acid volume of 45.645.6 liters.
x2+50x1400=0    (x+70)(x20)=0    x=20x^2 + 50x - 1400 = 0 \implies (x+70)(x-20) = 0 \implies x = 20.
Discarding the negative root (x=70x = -70) because volume must be positive.

Anahtar Kavram

Multi-stage sequential mixture removal and replacement
Soru 87Soru

A oceanographic research institute uses three autonomous submersibles���Submersible A, Submersible B, and Submersible C—to perform high-resolution seabed mapping. Working together at their respective constant rates, Submersible A and Submersible B can complete a full mapping mission in 1515 hours. Working together at their respective constant rates, Submersible B and Submersible C can complete the same mapping mission in 2424 hours. During a specialized operation, Submersible A works alone for 66 hours, after which it is recalled. Submersible B then works alone for 1010 hours, after which Submersible C joins Submersible B, and both work together for an additional 1212 hours to complete the remaining portion of the mission. How many hours would it take Submersible A to complete the entire seabed mapping mission working alone at its constant rate?

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Cevap: 24

Cevap

24 hours
The option stating 24 is correct because setting up the system of work rates rA+rB=115r_A + r_B = \frac{1}{15} and rB+rC=124r_B + r_C = \frac{1}{24}, along with the multi-stage work equation 6rA+10rB+12(rB+rC)=16r_A + 10r_B + 12(r_B + r_C) = 1, allows us to eliminate rCr_C and solve for rA=124r_A = \frac{1}{24}. Taking the reciprocal gives 24 hours.

Adım Adım Çözüm

1
Define rate variables and set up combined rate equations.
Let rAr_A, rBr_B, and rCr_C be the hourly rates of Submersibles A, B, and C respectively (in fraction of mission per hour). We are given: (1) rA+rB=115r_A + r_B = \frac{1}{15} and (2) rB+rC=124r_B + r_C = \frac{1}{24}.
Work rates are additive reciprocals of completion times for constant-rate work problems.
2
Express total mission work completed in the multi-stage operation.
6rA+10rB+12(rB+rC)=16r_A + 10r_B + 12(r_B + r_C) = 1, which simplifies to 6rA+22rB+12rC=16r_A + 22r_B + 12r_C = 1.
Total work equals the sum of work done across all sequential operational phases.
3
Substitute equation (2) into the multi-stage work equation.
Since rC=124rBr_C = \frac{1}{24} - r_B, we get 6rA+22rB+12(124rB)=1    6rA+10rB+12=1    6rA+10rB=126r_A + 22r_B + 12\left(\frac{1}{24} - r_B\right) = 1 \implies 6r_A + 10r_B + \frac{1}{2} = 1 \implies 6r_A + 10r_B = \frac{1}{2}.
Substituting rCr_C eliminates one variable, reducing the system to two equations in rAr_A and rBr_B.
4
Solve the two-variable system for rAr_A.
Multiply equation (1) by 1010 to get 10rA+10rB=1015=2310r_A + 10r_B = \frac{10}{15} = \frac{2}{3}. Subtract 6rA+10rB=126r_A + 10r_B = \frac{1}{2} from this to get 4rA=2312=16    rA=1244r_A = \frac{2}{3} - \frac{1}{2} = \frac{1}{6} \implies r_A = \frac{1}{24}.
Eliminating rBr_B isolates Submersible A's rate.
5
Calculate the time taken by Submersible A working alone.
Time =1rA=11/24=24= \frac{1}{r_A} = \frac{1}{1/24} = 24 hours.
Completion time is the reciprocal of the hourly work rate.

Anahtar Kavram

System of Work Rate Equations for Multi-Stage Combined Work
Tahmini Süre:2m 30s
Soru 88Soru

A barista has 4040 ounces of a flavored drink mixture that is 30%30\% syrup by volume. How many ounces of pure water must be added to reduce the syrup concentration to 24%24\% by volume?

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Cevap: 10

Cevap

10 ounces of pure water must be added.
Adding 10 ounces of pure water increases the total volume of the mixture from 40 ounces to 50 ounces while keeping the volume of pure syrup constant at 12 ounces. The resulting concentration is 12 / 50 = 0.24, or 24% by volume.

Adım Adım Çözüm

1
Calculate the volume of pure syrup present in the initial mixture
1212 ounces of syrup
The initial 40-ounce mixture contains 30% syrup by volume (40×0.30=1240 \times 0.30 = 12).
2
Set up the concentration equation after adding xx ounces of pure water
1240+x=0.24\frac{12}{40 + x} = 0.24
Adding pure water increases the total volume to 40+x40 + x ounces without changing the amount of pure syrup.
3
Solve the linear equation for xx
x=10x = 10
Multiplying both sides by 40+x40 + x yields 12=9.6+0.24x12 = 9.6 + 0.24x, which simplifies to 2.4=0.24x2.4 = 0.24x, giving x=10x = 10.

Anahtar Kavram

Dilution of a mixture by adding pure solvent
Soru 89Soru

In a corporate workshop of 8080 executives, 5252 executives attended the Leadership module and 4040 executives attended the Negotiation module. If 1818 executives attended neither module, how many executives attended both modules?

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Cevap: 30

Cevap

30 executives attended both modules.
Applying the formula Total=Group A+Group BBoth+Neither\text{Total} = \text{Group A} + \text{Group B} - \text{Both} + \text{Neither} yields 80=52+40Both+1880 = 52 + 40 - \text{Both} + 18. Simplifying gives 80=110Both80 = 110 - \text{Both}, so the number of executives who attended both modules is 3030.

Adım Adım Çözüm

1
Determine the number of executives who attended at least one of the two modules.
Executives attending at least one module = 8018=6280 - 18 = 62.
Subtracting those who attended neither module from the total gives the union of the two sets.
2
Apply the inclusion-exclusion principle to find the intersection of the two sets.
Both=Leadership+NegotiationAt least one=52+4062=30\text{Both} = \text{Leadership} + \text{Negotiation} - \text{At least one} = 52 + 40 - 62 = 30.
Summing the participants of each module double-counts those who attended both, so subtracting the number attending at least one module isolates the overlap.

Anahtar Kavram

Two-Set Overlapping Sets Formula (Inclusion-Exclusion Principle)
Tahmini Süre:1m 0s
Soru 90Soru

At a software firm, an audit of 200 developers evaluated proficiency in three programming languages: Python, Java, and C++.

- 120 developers are proficient in Python.
- 105 developers are proficient in Java.
- 95 developers are proficient in C++.
- 15 developers are proficient in all three languages.
- 10 developers are proficient in none of the three languages.
- The ratio of the number of developers proficient in BOTH Python and Java ONLY to the number of developers proficient in BOTH Python and C++ ONLY is 3:23 : 2.
- The number of developers proficient in ONLY Java is equal to the number of developers proficient in ONLY C++.

How many developers are proficient in ONLY Python?

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Cevap: 55

Cevap

55 developers are proficient in ONLY Python.
By decomposing the 3-set Venn diagram into 7 mutually exclusive regions, the given ratio d:e=3:2d : e = 3 : 2 gives d=3kd = 3k and e=2ke = 2k. Comparing the totals for Java (105105) and C++ (9595) under the condition that Java-only equals C++-only shows that k=10k = 10. Thus, 3030 developers are in Python and Java only, 2020 are in Python and C++ only, and 1515 are in all three. Subtracting these three regions from the total 120120 Python developers yields 120302015=55120 - 30 - 20 - 15 = 55 proficient in Python only.

Adım Adım Çözüm

1
Assign variables to the Venn diagram regions and incorporate given ratios.
Represent d=PJ only=3kd = |P \cap J \text{ only}| = 3k and e=PC only=2ke = |P \cap C \text{ only}| = 2k, with g=15g = 15 and None=10\text{None} = 10.
Establishing explicit variables for non-overlapping regions simplifies system solving.
2
Set up set total equations for J|J| and C|C| to solve for kk.
J    b+3k+f=90|J| \implies b + 3k + f = 90 and C    b+2k+f=80|C| \implies b + 2k + f = 80. Subtracting yields k=10k = 10.
Since b=cb = c (Java only = C++ only), subtracting the two set equations eliminates bb and ff, directly giving kk.
3
Calculate the region values dd and ee, then solve for a=P onlya = |P \text{ only}|.
d=30d = 30, e=20e = 20. Then a=120(30+20+15)=55a = 120 - (30 + 20 + 15) = 55.
Subtracting all other regions of set PP from the total proficient in Python isolates those proficient ONLY in Python.

Anahtar Kavram

Three-Set Overlapping Sets and Region Decomposition
Soru 91Soru

Vessel A contains 4040 kilograms of an organic fertilizer mixture that is 60%60\% Nitrogen by weight. Vessel B contains 6060 kilograms of a fertilizer mixture that is 20%20\% Nitrogen by weight. First, xx kilograms of the mixture are removed from Vessel A and transferred into Vessel B, where the contents are thoroughly mixed. Then, xx kilograms of the newly formed mixture in Vessel B are transferred back into Vessel A. If the final mixture in Vessel A is 50%50\% Nitrogen by weight, what is the value of xx?

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Cevap: 1212

Cevap

The value of xx is 1212.
The correct answer of 12 kg accounts for the dynamic concentration change in Vessel B after the initial transfer. When x=12x = 12 kg is moved from Vessel A to Vessel B, Vessel B contains 72 kg total mixture with 19.2 kg Nitrogen, giving a concentration of 26.67%26.67\% (or 415\frac{4}{15}). Transferring 12 kg of this mixture back to Vessel A adds 12×415=3.212 \times \frac{4}{15} = 3.2 kg Nitrogen to the 16.8 kg Nitrogen remaining in Vessel A, resulting in exactly 20 kg of Nitrogen in a 40 kg total mixture (50%50\% concentration).

Adım Adım Çözüm

1
Calculate the initial mass of Nitrogen in each vessel.
Vessel A initially has 0.60×40=240.60 \times 40 = 24 kg of Nitrogen. Vessel B initially has 0.20×60=120.20 \times 60 = 12 kg of Nitrogen.
Tracking exact solute quantities is required for setting up the mixture conservation equation.
2
Determine the amount of Nitrogen in both vessels after transferring xx kg from Vessel A to Vessel B.
Vessel A retains (40x)(40 - x) kg of solution containing (240.60x)(24 - 0.60x) kg of Nitrogen. Vessel B now has (60+x)(60 + x) kg of total mixture containing (12+0.60x)(12 + 0.60x) kg of Nitrogen.
The solution removed from Vessel A carries Nitrogen at a concentration of 60%.
3
Express the concentration of Nitrogen in Vessel B prior to the second transfer.
The concentration in Vessel B is CB=12+0.60x60+xC_B = \frac{12 + 0.60x}{60 + x}.
Concentration equals total mass of Nitrogen divided by total mass of the mixture in Vessel B.
4
Formulate the equation for the final Nitrogen mass in Vessel A after returning xx kg from Vessel B.
Final Nitrogen in Vessel A: (240.60x)+x(12+0.60x60+x)=0.50×40=20(24 - 0.60x) + x \cdot \left(\frac{12 + 0.60x}{60 + x}\right) = 0.50 \times 40 = 20.
The final volume of Vessel A is restored to 40 kg with a target concentration of 50%.
5
Solve the algebraic equation for xx.
40.60x+12x+0.60x260+x=0    (40.60x)(60+x)+12x+0.60x2=0    240+4x36x0.60x2+12x+0.60x2=0    24020x=0    x=124 - 0.60x + \frac{12x + 0.60x^2}{60 + x} = 0 \implies (4 - 0.60x)(60 + x) + 12x + 0.60x^2 = 0 \implies 240 + 4x - 36x - 0.60x^2 + 12x + 0.60x^2 = 0 \implies 240 - 20x = 0 \implies x = 12.
Multiplying through by (60+x)(60 + x) cancels the non-linear x2x^2 terms, yielding a linear relation.

Anahtar Kavram

Two-Stage Transfer and Dilution
Tahmini Süre:2m 30s
Soru 92Soru

A regional logistics company maintains a fleet consisting of delivery vans, medium trucks, and heavy cargo trucks in the initial ratio of 3:4:53 : 4 : 5, respectively. After the company retires 4 delivery vans, purchases 12 medium trucks, and purchases 6 heavy cargo trucks, the ratio of delivery vans to heavy cargo trucks becomes 1:21 : 2. What was the total number of vehicles in the fleet initially?

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Cevap: 168

Cevap

168
The initial ratio of 3:4:53 : 4 : 5 implies that the number of vans, medium trucks, and heavy cargo trucks can be represented as 3x3x, 4x4x, and 5x5x for some positive multiplier xx. The initial total fleet is 3x+4x+5x=12x3x + 4x + 5x = 12x. Modifying the counts according to the problem gives 3x43x - 4 vans and 5x+65x + 6 heavy trucks. Equating their ratio to 1/21/2 produces 3x45x+6=12\frac{3x - 4}{5x + 6} = \frac{1}{2}. Cross-multiplying gives 6x8=5x+66x - 8 = 5x + 6, which simplifies to x=14x = 14. Multiplying 1414 by the initial sum of ratio units (1212) yields the correct initial total of 168168.

Adım Adım Çözüm

1
Define initial quantities using a common multiplier xx
Delivery vans =3x= 3x, Medium trucks =4x= 4x, Heavy cargo trucks =5x= 5x. Initial total fleet =3x+4x+5x=12x= 3x + 4x + 5x = 12x.
Expressing each vehicle count in terms of xx preserves the given initial ratio of 3:4:53 : 4 : 5.
2
Formulate the equation based on the updated vehicle counts and new ratio
New number of vans =3x4= 3x - 4. New number of heavy cargo trucks =5x+6= 5x + 6. Equation: 3x45x+6=12\frac{3x - 4}{5x + 6} = \frac{1}{2}.
The problem states that after retiring 4 vans and adding 6 heavy cargo trucks, the ratio of vans to heavy cargo trucks becomes 1:21 : 2.
3
Solve the algebraic equation for xx
2(3x4)=1(5x+6)    6x8=5x+6    x=142(3x - 4) = 1(5x + 6) \implies 6x - 8 = 5x + 6 \implies x = 14.
Cross-multiplying eliminates the fraction and isolates xx.
4
Calculate the initial total number of vehicles
Initial total =12x=12×14=168= 12x = 12 \times 14 = 168.
Substituting x=14x = 14 into the initial total expression 12x12x yields the total fleet size prior to any modifications.

Anahtar Kavram

Multi-part ratio scaling and structural algebraic modeling under quantity changes
Soru 93Soru

A retailer purchases a jacket for $80. The retailer marks up the purchase price by 25% to establish a list price. During a clearance sale, the jacket is sold at a 10% discount off the list price. What is the retailer's net profit on the sale of the jacket?

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Cevap: $10

Cevap

The retailer's net profit is $10.
To find the net profit, first determine the list price by adding a 25% markup to the cost price of 80,whichgives80, which gives 100. Then apply a 10% discount to the list price of 100,yieldingasellingpriceof100, yielding a selling price of 90. Subtracting the initial cost of 80from80 from 90 gives a net profit of $10.

Adım Adım Çözüm

1
Calculate the list price by applying the 25% markup to the cost price.
List Price=$80+(0.25×$80)=$80+$20=$100\text{List Price} = \$80 + (0.25 \times \$80) = \$80 + \$20 = \$100
Markup is calculated as a percentage of the original cost price.
2
Calculate the selling price after applying the 10% discount to the list price.
Selling Price=$100(0.10×$100)=$100$10=$90\text{Selling Price} = \$100 - (0.10 \times \$100) = \$100 - \$10 = \$90
Discounts are calculated based on the list price, not the original cost price.
3
Calculate the net profit by subtracting the cost price from the selling price.
Net Profit=Selling PriceCost Price=$90$80=$10\text{Net Profit} = \text{Selling Price} - \text{Cost Price} = \$90 - \$80 = \$10
Profit is the difference between the final selling price and the initial purchase cost.

Anahtar Kavram

Profit, Loss, and Markup with Successive Percentages
Soru 94Soru

At a research foundation, annual grant funding was initially allocated among three divisions—Artificial Intelligence, Biotechnology, and Renewable Energy—in the ratio 7:4:37 : 4 : 3, respectively. At mid-year, the foundation redistributed the funding by transferring $10\$10 million from the Artificial Intelligence division to the Renewable Energy division, while the Biotechnology division's funding remained unchanged. After this transfer, the ratio of Artificial Intelligence funding to Renewable Energy funding became 3:23 : 2. What was the total annual grant funding, in millions of dollars, allocated across all three divisions?

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Cevap: 140

Cevap

The total annual grant funding allocated across all three divisions was 140140 million dollars.
By setting the initial funding amounts to 7x7x, 4x4x, and 3x3x million dollars, the total funding is 14x14x. The transfer alters Artificial Intelligence funding to 7x107x - 10 and Renewable Energy funding to 3x+103x + 10. Setting their ratio to 32\frac{3}{2} yields the equation 2(7x10)=3(3x+10)2(7x - 10) = 3(3x + 10), which simplifies to 5x=505x = 50, giving x=10x = 10. Thus, total funding is 14×10=14014 \times 10 = 140 million dollars.

Adım Adım Çözüm

1
Define variables for the initial allocation based on the ratio 7:4:37 : 4 : 3.
Artificial Intelligence funding =7x= 7x, Biotechnology funding =4x= 4x, Renewable Energy funding =3x= 3x, and total funding =7x+4x+3x=14x= 7x + 4x + 3x = 14x.
Ratios represent relative parts of a whole multiplier xx.
2
Model the redistribution of funds.
New Artificial Intelligence funding =7x10= 7x - 10; New Renewable Energy funding =3x+10= 3x + 10.
Transferring $10\$10 million decreases Artificial Intelligence funding by 1010 and increases Renewable Energy funding by 1010.
3
Equate the new ratio to 3:23 : 2 and solve for xx.
7x103x+10=32    14x20=9x+30    5x=50    x=10\frac{7x - 10}{3x + 10} = \frac{3}{2} \implies 14x - 20 = 9x + 30 \implies 5x = 50 \implies x = 10.
Cross-multiplication converts ratio relationships into a solvable linear equation.
4
Calculate the total annual grant funding.
Total funding =14x=14×10=140= 14x = 14 \times 10 = 140 million dollars.
Substituting x=10x = 10 into the total funding expression 14x14x gives the final answer.

Anahtar Kavram

Algebraic setup of multi-part ratio redistribution problems
Soru 95Soru

An agricultural processing plant produces a livestock feed blend consisting of corn, soybeans, and oats in an initial weight ratio of 5:3:25 : 3 : 2, respectively. To increase the protein content of a 1,200 kg1,200\text{ kg} batch of this blend, a technician removes a certain quantity of oats and replaces it with an equal weight of soybeans. If the resulting weight ratio of corn to soybeans to oats becomes 10:9:110 : 9 : 1, how many kilograms of oats were replaced by soybeans?

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Cevap: 180

Cevap

180 kg of oats were replaced by soybeans.
The correct answer demonstrates that since corn is unchanged (600 kg600\text{ kg}), it corresponds to 1010 parts in the new 10:9:110 : 9 : 1 ratio. This yields 60 kg60\text{ kg} per part in the new ratio. Oats decrease from 240 kg240\text{ kg} (22 initial parts of 120 kg120\text{ kg}) to 60 kg60\text{ kg} (11 final part of 60 kg60\text{ kg}), indicating that 180 kg180\text{ kg} of oats were replaced by an equal weight of soybeans.

Adım Adım Çözüm

1
Determine the initial weight of each component in the 1,200 kg batch.
The initial ratio is 5:3:25 : 3 : 2, giving a total of 5+3+2=105 + 3 + 2 = 10 parts. Each part corresponds to 1,200 kg10=120 kg\frac{1,200\text{ kg}}{10} = 120\text{ kg}. Therefore: Corn =5×120=600 kg= 5 \times 120 = 600\text{ kg}, Soybeans =3×120=360 kg= 3 \times 120 = 360\text{ kg}, Oats =2×120=240 kg= 2 \times 120 = 240\text{ kg}.
Finding the absolute initial quantities provides baseline values before the substitution occurs.
2
Analyze the invariant quantity after the substitution.
Since oats are replaced by an equal weight of soybeans, the total weight of the batch remains 1,200 kg1,200\text{ kg}, and the weight of corn remains unchanged at 600 kg600\text{ kg}.
Identifying unchanged quantities allows direct scaling of the new ratio.
3
Calculate the value of one ratio unit in the new ratio.
The new ratio of corn to soybeans to oats is 10:9:110 : 9 : 1. The 600 kg600\text{ kg} of corn represents 1010 parts of the new ratio. Thus, 1 part=600 kg10=60 kg1\text{ part} = \frac{600\text{ kg}}{10} = 60\text{ kg}. Alternatively, total parts =10+9+1=20= 10 + 9 + 1 = 20 parts, so 1 part=1,200 kg20=60 kg1\text{ part} = \frac{1,200\text{ kg}}{20} = 60\text{ kg}.
Determining the scale of the new ratio allows finding the new weight of each ingredient.
4
Compute the weight of oats replaced.
The new oats weight is 1×60 kg=60 kg1 \times 60\text{ kg} = 60\text{ kg}. The replaced quantity is Initial Oats - Final Oats =240 kg60 kg=180 kg= 240\text{ kg} - 60\text{ kg} = 180\text{ kg}.
The difference between initial and final oat weights equals the replaced quantity.

Anahtar Kavram

Solving multi-part ratio changes using invariant quantities and constant total mass scaling.
Tahmini Süre:2m 0s
Soru 96Soru

A storage tank is completely filled with 150150 liters of a solution containing Compounds X, Y, and Water in a ratio of 2:3:52:3:5 by volume. First, 3030 liters of the mixture are drained and replaced with 3030 liters of a liquid mixture that is 20%20\% Compound Y by volume. Next, 5050 liters of the resulting mixture are drained and replaced with 5050 liters of another liquid mixture that is 70%70\% Compound Y by volume. What is the percentage of Compound Y, by volume, in the final mixture?

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Cevap: 42

Cevap

The final mixture contains 42% of Compound Y by volume.
To find the final concentration, track the exact volume of Compound Y through both stages. Initially, the tank holds 150×310=45150 \times \frac{3}{10} = 45 liters of Y. In the first replacement, draining 3030 liters (20%20\% of the tank) leaves 80%80\% of Y, which is 3636 liters; adding 3030 liters of 20%20\% Y mixture adds 66 liters, bringing Y to 4242 liters. In the second replacement, draining 5050 liters (13\frac{1}{3} of the tank) leaves 23\frac{2}{3} of Y, which is 2828 liters; adding 5050 liters of 70%70\% Y mixture adds 3535 liters, yielding 6363 liters of Y. The final concentration is 63150×100%=42%\frac{63}{150} \times 100\% = 42\%.

Adım Adım Çözüm

1
Calculate initial volume of Compound Y in the tank
Initial Y volume = 45 liters
The ratio X:Y:Water is 2:3:5, giving a total of 2 + 3 + 5 = 10 parts. The fraction of Y is 3/10. For a 150-liter tank, Y = 150 * (3/10) = 45 liters.
2
Calculate Compound Y after the first draining and replacement cycle
Compound Y volume after first replacement = 42 liters
Draining 30 liters removes 30 / 150 = 1/5 of the mixture. Y remaining = 45 * (1 - 1/5) = 36 liters. Replacing with 30 liters of 20% Y adds 30 * 0.20 = 6 liters of Y. Total Y = 36 + 6 = 42 liters.
3
Calculate Compound Y after the second draining and replacement cycle
Compound Y volume after second replacement = 63 liters
Draining 50 liters removes 50 / 150 = 1/3 of the current mixture. Y remaining = 42 * (1 - 1/3) = 28 liters. Replacing with 50 liters of 70% Y adds 50 * 0.70 = 35 liters of Y. Total Y = 28 + 35 = 63 liters.
4
Compute final percentage of Compound Y
42%
The final volume of the tank remains 150 liters. Percentage of Y = (63 / 150) * 100% = 42%.

Anahtar Kavram

Multi-Stage Mixture Removal and Replacement
Soru 97Soru

A textile manufacturing plant uses two automated weaving looms, Loom PP and Loom QQ, to produce standardized fabric orders. Working alone at its constant rate, Loom PP can complete a full fabric order in 88 hours, while Loom QQ working alone at its constant rate can complete the same order in 1212 hours. Loom PP begins working on a full order alone. After 33 hours, Loom QQ joins Loom PP, and both looms work together at their respective constant rates until the order is completed. How many total hours does it take, from the moment Loom PP begins, to complete the entire fabric order?

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Cevap: 66

Cevap

66 hours
In the first 33 hours, Loom PP completes 3×18=383 \times \frac{1}{8} = \frac{3}{8} of the job, leaving 58\frac{5}{8} of the job remaining. When Loom QQ joins, their combined rate is 18+112=524\frac{1}{8} + \frac{1}{12} = \frac{5}{24} of the job per hour. The time needed to complete the remaining 58\frac{5}{8} of the job is 5/85/24=3\frac{5/8}{5/24} = 3 hours. Adding the initial 33 hours of solo work gives a total of 66 hours.

Adım Adım Çözüm

1
Determine the individual hourly work rates of Loom PP and Loom QQ.
Rate of Loom P=18P = \frac{1}{8} order/hour; Rate of Loom Q=112Q = \frac{1}{12} order/hour.
Work rate is the reciprocal of the total time needed to complete one full unit of work.
2
Calculate the fraction of the order completed by Loom PP during its 33 hours of solo operation.
Work completed by Loom P=3×18=38P = 3 \times \frac{1}{8} = \frac{3}{8} of the order.
Work done equals rate multiplied by time spent working.
3
Find the remaining fraction of the order to be completed.
Remaining work = 138=581 - \frac{3}{8} = \frac{5}{8} of the order.
The total job represents 11 whole unit of work.
4
Calculate the combined work rate when both looms operate together.
Combined rate = 18+112=324+224=524\frac{1}{8} + \frac{1}{12} = \frac{3}{24} + \frac{2}{24} = \frac{5}{24} order/hour.
When entities work together, their individual rates add up.
5
Determine the time required for both looms together to finish the remaining work.
Time together = 5/85/24=58×245=3\frac{5/8}{5/24} = \frac{5}{8} \times \frac{24}{5} = 3 hours.
Time equals remaining work divided by the combined work rate.
6
Calculate the total time from start to finish.
Total time = 3 hours (solo)+3 hours (combined)=6 hours3 \text{ hours (solo)} + 3 \text{ hours (combined)} = 6 \text{ hours}.
The total elapsed time is the sum of the solo operating time and the combined operating time.

Anahtar Kavram

Work Rate and Combined Work
Tahmini Süre:2m 0s
Soru 98Soru

A delivery van travels from Warehouse A to Warehouse B at a constant speed of 4040 miles per hour and returns along the exact same route from Warehouse B to Warehouse A at a constant speed of 6060 miles per hour. If the distance between Warehouse A and Warehouse B is 120120 miles, what is the average speed of the delivery van for the entire round trip, in miles per hour?

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Cevap: 48

Cevap

The average speed for the entire round trip is 4848 miles per hour.
To find the average speed for the round trip, divide the total distance (240240 miles) by the total time taken (55 hours). The time taken for the first leg is 12040=3\frac{120}{40} = 3 hours, and for the return leg is 12060=2\frac{120}{60} = 2 hours. Thus, the average speed is 2405=48\frac{240}{5} = 48 miles per hour.

Adım Adım Çözüm

1
Determine the total distance traveled during the round trip.
The distance from Warehouse A to B is 120120 miles, making the total round-trip distance 120+120=240120 + 120 = 240 miles.
Average speed requires the total distance for all legs of the journey.
2
Calculate time taken for each leg and find total time.
Time taken at 4040 mph is 12040=3\frac{120}{40} = 3 hours. Time taken at 6060 mph is 12060=2\frac{120}{60} = 2 hours. Total time = 3+2=53 + 2 = 5 hours.
Time equals distance divided by rate (t=drt = \frac{d}{r}).
3
Divide total distance by total time to obtain average speed.
Average speed = 240 miles5 hours=48\frac{240 \text{ miles}}{5 \text{ hours}} = 48 miles per hour.
The defining formula for average speed is Average Speed=Total DistanceTotal Time\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}}.

Anahtar Kavram

Average speed for a multi-leg journey is always total distance divided by total time, not the arithmetic mean of the speeds.
Soru 99Soru

At an intellectual property law firm, a senior partner reviewed 180180 patent applications across three technical domains: Artificial Intelligence, Biotechnology, and Clean Energy. The audit revealed that 2525 applications belonged to none of these three domains. Furthermore, 9090 applications involved Artificial Intelligence, 8585 involved Biotechnology, and 8080 involved Clean Energy. If the number of applications that belonged to exactly two of these domains was three times the number of applications that belonged to all three domains, how many patent applications belonged to exactly one domain?

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Cevap: 75

Cevap

The total number of patent applications that belonged to exactly one domain is 7575.
The total number of applications in at least one domain is 18025=155180 - 25 = 155. Let E1E_1 be the number of applications in exactly one domain, E2E_2 in exactly two domains, and xx in all three domains. The total union is E1+E2+x=155E_1 + E_2 + x = 155, while the sum of individual set sizes is A+B+C=E1+2E2+3x=90+85+80=255|A| + |B| + |C| = E_1 + 2E_2 + 3x = 90 + 85 + 80 = 255. Subtracting the union equation from the sum equation gives E2+2x=100E_2 + 2x = 100. Given E2=3xE_2 = 3x, substituting gives 5x=100    x=205x = 100 \implies x = 20, which implies E2=60E_2 = 60. Finally, subtracting E2E_2 and xx from the total union yields E1=1556020=75E_1 = 155 - 60 - 20 = 75.

Adım Adım Çözüm

1
Calculate the total number of applications in at least one domain
ABC=18025=155|A \cup B \cup C| = 180 - 25 = 155
Subtracting the applications belonging to none of the domains from the overall total yields the total number of unique applications covered by the three domains combined.
2
Formulate regional Venn diagram equations
E1+E2+x=155E_1 + E_2 + x = 155 and E1+2E2+3x=255E_1 + 2E_2 + 3x = 255
Summing individual set counts counts elements in exactly two domains twice and elements in all three domains three times.
3
Deduce the relationship between E2E_2 and xx
E2+2x=100E_2 + 2x = 100
Subtracting the equation for total union from the sum of individual sets isolates the overcounted regions.
4
Use the given proportion E2=3xE_2 = 3x to solve for xx and E2E_2
x=20x = 20 and E2=60E_2 = 60
Substituting E2=3xE_2 = 3x into E2+2x=100E_2 + 2x = 100 gives 5x=1005x = 100, so x=20x = 20 and E2=60E_2 = 60.
5
Find the number of applications belonging to exactly one domain (E1E_1)
E1=75E_1 = 75
Subtracting the count of applications in exactly two domains (6060) and all three domains (2020) from the total union (155155) gives 1556020=75155 - 60 - 20 = 75.

Anahtar Kavram

Three-Set Venn Diagram Region Partitioning
Soru 100Soru

In a software development department, the numbers of Frontend developers, Backend developers, and DevOps engineers were initially in the ratio of 4:5:34 : 5 : 3, respectively. After the department hired 66 additional DevOps engineers, with no changes to the number of Frontend or Backend developers, the ratio of Backend developers to DevOps engineers became 1:11 : 1. What is the total number of developers and engineers in the department after these new hires?

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Cevap: 42

Cevap

The total number of developers and engineers in the department after the new hires is 42.
By setting the initial counts of Frontend developers, Backend developers, and DevOps engineers as 4x4x, 5x5x, and 3x3x, adding 6 to DevOps yields 3x+63x + 6. Equating Backend and DevOps counts gives 5x=3x+65x = 3x + 6, so x=3x = 3. Substituting x=3x = 3 into the post-hire counts gives 12 Frontend, 15 Backend, and 15 DevOps, summing to a total of 42 employees.

Adım Adım Çözüm

1
Define initial quantities using a common ratio multiplier.
Let the initial numbers of Frontend developers, Backend developers, and DevOps engineers be 4x4x, 5x5x, and 3x3x, respectively.
Ratios allow representing unknown totals in terms of a single multiplier xx.
2
Express the updated counts after hiring new DevOps engineers.
Frontend = 4x4x, Backend = 5x5x, and DevOps = 3x+63x + 6.
Only the DevOps group increases by 6 while other group sizes remain unchanged.
3
Set up an equation based on the new Backend-to-DevOps ratio of 1:11 : 1.
5x=3x+6    2x=6    x=35x = 3x + 6 \implies 2x = 6 \implies x = 3.
A 1:11 : 1 ratio means the number of Backend developers equals the new number of DevOps engineers.
4
Calculate the final total number of employees.
Frontend = 4(3)=124(3) = 12, Backend = 5(3)=155(3) = 15, DevOps = 3(3)+6=153(3) + 6 = 15. Total = 12+15+15=4212 + 15 + 15 = 42.
Summing all three roles after adding the 6 new hires gives the final count.

Anahtar Kavram

Ratio scaling and setting up algebraic equations from modified multi-part ratios.
Tahmini Süre:1m 30s
ÖncekiSayfa 5 / 10Sonraki
Word Problems and Applied Math Alıştırma Soruları — GMAT — Sayfa 5 | Examkin