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Home › Mathematics › Time and Work

Time and Work — Mathematics Questions & Practice

Practise 377 Time and Work questions from Mathematics for competitive exams such as UPSC, Banking, SSC and Railway. Read the worked questions below, check every answer with an explanation, and track what you get wrong.

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Practice questions on Time and Work — with answers

Try each question first, then open the answer. Explanations are included.

1. A can do a piece of work in 10 days and B can do it in 15 days. How many days will they take to complete it together?

  1. A5 days
  2. B6 days
  3. C7 days
  4. D8 days
Show answer

Answer: B

Combined rate=1/10+1/15=1/6. So together they take 6 days.

2. A, B and C can do a work in 8, 12 and 24 days respectively. How many days will they take to complete it together?

  1. A3 days
  2. B4 days
  3. C5 days
  4. D6 days
Show answer

Answer: B

Combined rate=1/8+1/12+1/24=3/24+2/24+1/24=6/24=1/4. So together they take 4 days.

3. A can complete a work alone in 20 days. A and B together complete it in 12 days. In how many days can B alone complete the work?

  1. A25 days
  2. B28 days
  3. C30 days
  4. D32 days
Show answer

Answer: C

B's rate=1/12-1/20=5/60-3/60=2/60=1/30. So B alone takes 30 days.

4. A can do a piece of work in 6 days. A and B together can do it in 4 days. In how many days can B alone do the work?

  1. A10 days
  2. B11 days
  3. C12 days
  4. D14 days
Show answer

Answer: C

B's rate=1/4-1/6=3/12-2/12=1/12. So B alone takes 12 days.

5. A and B can complete a work in 12 and 15 days respectively. They work together for 4 days, after which A leaves. In how many more days will B alone finish the remaining work?

  1. A5 days
  2. B6 days
  3. C7 days
  4. D8 days
Show answer

Answer: B

Combined rate=1/12+1/15=3/20. Work done in 4 days=12/20=3/5. Remaining=2/5. B's rate=1/15, so days needed=(2/5)/(1/15)=6 days.

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