Time & Work / Pipes & Cisterns

SSC CGL · Quantitative Aptitude · 35 practice questions with answers and explanations: 12 Easy, 11 Medium, 12 Hard.

Sample questions

Sample Easy question 1

If 5 workers can complete a task in 12 days, how many days will 10 workers take?

  1. 4
  2. 5
  3. 6
  4. 7
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Answer: C. Doubling the workers halves the time: 12/2 = 6 days.

Sample Medium question 2

A does twice the work of B in the same time. If B alone can complete a job in 24 days, in how many days can A and B together complete it?

  1. 6 days
  2. 7 days
  3. 8 days
  4. 9 days
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Answer: C. A's rate = 2 × B's rate = 2/24 = 1/12. Combined rate = 1/12 + 1/24 = 2/24+1/24 = 3/24 = 1/8, so together they take 8 days.

Sample Hard question 3

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. 28
  3. 30
  4. 32
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Answer: C. 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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