Time & Work / Pipes & Cisterns

J&K Bank PO · Quantitative Aptitude · 115 practice questions with answers and explanations: 44 Easy, 70 Medium, 1 Hard.

Sample questions

Sample Easy question 1

A can finish a piece of work in 18 days and B can finish it in 36 days. Working together, in how many days will they finish it?

  1. 11
  2. 13
  3. 27
  4. 12
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Answer: D. Rate of A + B = 1/18 + 1/36 = 54/648, so they take 648/54 = 12 days.

Sample Easy question 2

A can complete a work in 12 days. After A has worked for 3 days, what fraction of the work is still left?

  1. 3/4
  2. 1/4
  3. 4/3
  4. 3/1
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Answer: A. Work done = 3/12, so work left = 1 − 3/12 = 3/4.

Sample Easy question 3

A and B together can finish a work in 12 days. A alone can finish it in 18 days. In how many days can B alone finish it?

  1. 36
  2. 24
  3. 18
  4. 30
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Answer: A. 1/B = 1/12 − 1/18 = 1/36, so B alone takes 36 days.

Sample Medium question 4

A, B and C can complete a piece of work in 12, 15 and 60 days respectively. They start together. After 1 day A leaves, and after 3 more days C also leaves. In how many more days will B finish the remaining work?

  1. 9 3/4 days
  2. 8 3/4 days
  3. 7 3/4 days
  4. 10 3/4 days
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Answer: B. Work done in the first 1 day(s) = 1 × 1/6; work done in the next 3 day(s) by B and C = 3 × 1/12. Remaining work = 7/12, which B alone does in 8 3/4 days.

Sample Medium question 5

A, B and C can complete a piece of work in 12, 24 and 15 days respectively. They start together. After 3 days A leaves, and after 2 more days C also leaves. In how many more days will B finish the remaining work?

  1. 6 days
  2. 4 days
  3. 7 days
  4. 5 days
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Answer: D. Work done in the first 3 day(s) = 3 × 23/120; work done in the next 2 day(s) by B and C = 2 × 13/120. Remaining work = 5/24, which B alone does in 5 days.

Sample Medium question 6

A, B and C can complete a piece of work in 10, 15 and 60 days respectively. They start together. After 1 day A leaves, and after 1 more day C also leaves. In how many more days will B finish the remaining work?

  1. 11 days
  2. 10 days
  3. 13 days
  4. 12 days
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Answer: A. Work done in the first 1 day(s) = 1 × 11/60; work done in the next 1 day(s) by B and C = 1 × 1/12. Remaining work = 11/15, which B alone does in 11 days.

Sample Hard question 7

Together, A and B take 18 days to finish a job; A does half as much work as B in three-fourths of B's time. Find B's time alone.

  1. 25
  2. 30
  3. 28
  4. 32
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Answer: B. Working through the ratio gives A's rate as 2/(3x) where x is B's time; solving the combined rate equation gives x = 30 days.

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