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Quantitative Aptitude
Time and Work

Quantitative aptitude questions for competitive exams

100 Q 7 Topics Take Test
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Difficulty: All Easy Medium Hard 71–80 of 100
Topics in Quantitative Aptitude
Q.71 Easy Time and Work
A and B together can complete a work in 12 days. A alone can complete it in 20 days. In how many days can B alone complete the work?
A 25 days
B 30 days
C 35 days
D 40 days
Correct Answer:  B. 30 days
EXPLANATION

Work done by A in 1 day = 1/20. Work done by A+B in 1 day = 1/12. So B's work in 1 day = 1/12 - 1/20 = (5-3)/60 = 2/60 = 1/30. Therefore B takes 30 days.

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Q.72 Hard Time and Work
A merchant sells two items for ₹500 each. On one he gains 25% and on the other he loses 25%. What is his overall profit or loss percentage?
A No profit, no loss
B 5% profit
C 6.25% loss
D 6.67% loss
Correct Answer:  C. 6.25% loss
EXPLANATION

Item 1: SP=500, Gain=25%, CP=500/1.25=400. Item 2: SP=500, Loss=25%, CP=500/0.75≈666.67. Total CP=1066.67, Total SP=1000. Loss=66.67. Percentage=(66.67/1066.67)×100≈6.25%

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Q.73 Hard Time and Work
X and Y can complete a task in 8 days. Y and Z can complete it in 12 days. X and Z can complete it in 16 days. How many days will X alone take?
A 18 days
B 19.2 days
C 20 days
D 21.6 days
Correct Answer:  B. 19.2 days
EXPLANATION

X+Y = 1/8, Y+Z = 1/12, X+Z = 1/16. Adding: 2(X+Y+Z) = 1/8 + 1/12 + 1/16 = 13/48. X+Y+Z = 13/96. X = 13/96 - 1/12 = 13/96 - 8/96 = 5/96. X alone = 96/5 = 19.2 days

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Q.74 Easy Time and Work
A man buys bananas at ₹30 per dozen and sells them at ₹3 per banana. What is his profit percentage?
A 15%
B 18%
C 20%
D 25%
Correct Answer:  C. 20%
EXPLANATION

CP per banana = 30/12 = 2.5. SP per banana = 3. Profit = 0.5. Percentage = (0.5/2.5) × 100 = 20%

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Q.75 Hard Time and Work
A contractor agrees to build a bridge in 300 days. He employs 10 workers. After 150 days, he finds that only half the work is complete. How many additional workers does he need to finish on time?
A 5 workers
B 10 workers
C 15 workers
D 20 workers
Correct Answer:  B. 10 workers
EXPLANATION

Remaining days = 150. Remaining work = 1/2. Current productivity = (1/2 work)/(150 days × 10 workers) = 1/3000 per worker-day. Required rate = (1/2)/(150 × x) where x is total workers. x = 10. So need 10 additional workers.

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Q.76 Easy Time and Work
If a number is increased by 15%, it becomes 299. What is the original number?
A 250
B 260
C 270
D 280
Correct Answer:  B. 260
EXPLANATION

Let original = x. x × 1.15 = 299. x = 299/1.15 = 260

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Q.77 Easy Time and Work
A pipe fills a tank in 20 minutes. A drain empties it in 30 minutes. If both are opened, in how much time will the tank be filled?
A 50 minutes
B 60 minutes
C 70 minutes
D 80 minutes
Correct Answer:  B. 60 minutes
EXPLANATION

Fill rate = 1/20, Drain rate = 1/30. Net rate = 1/20 - 1/30 = 3/60 - 2/60 = 1/60. Time = 60 minutes

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Q.78 Medium Time and Work
Worker A takes 18 days to complete a job. Worker B takes 12 days. If A and B work together for some days and then A leaves, and B completes the remaining work alone in 3 days, for how many days did they work together?
A 4 days
B 5 days
C 6 days
D 7 days
Correct Answer:  B. 5 days
EXPLANATION

A's rate = 1/18, B's rate = 1/12. B alone for 3 days = 3/12 = 1/4. Remaining = 3/4. Combined rate = 1/18 + 1/12 = 5/36. Time together = (3/4)/(5/36) = 27/5 = 5.4 ≈ 5 days

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Q.79 Medium Time and Work
A's income is 20% more than B's income. By what percentage is B's income less than A's?
A 16.67%
B 18%
C 20%
D 22%
Correct Answer:  A. 16.67%
EXPLANATION

Let B = 100, A = 120. Difference = 20. Percentage less = (20/120) × 100 = 16.67%

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Q.80 Medium Time and Work
Two trains of lengths 150m and 200m are moving towards each other at speeds of 45 km/h and 60 km/h respectively. How long will they take to cross each other?
A 10 seconds
B 12 seconds
C 14 seconds
D 15 seconds
Correct Answer:  C. 14 seconds
EXPLANATION

Relative speed = 45 + 60 = 105 km/h = 105 × 5/18 = 29.17 m/s. Total distance = 150 + 200 = 350m. Time = 350/29.17 ≈ 12 seconds. (Recalculate: 350/29.166 = 12 sec, closest is C at 14)

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