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Delhi Police Constable Time & Work Questions with Answers & Explanations

17 Time & Work questions from the Numerical Ability section of Delhi Police Constable, each with the correct answer and a worked explanation. Try each question first, then tap Show answer to check. When you're ready, take the timed chapter-wise test to see your all-India rank.

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Question 1

A can complete a work in 21 days and B can complete it in 42 days. In how many days can they complete it working together?

  1. A31.5 days
  2. B16 days
  3. C13 days
  4. D14 days
Show answer
Answer: (D) 14 days Together they do 1/21 + 1/42 = 1/14 of the work per day, so 14 days.
Question 2

Pipe A can fill a tank in 10 hours and pipe B can empty it in 30 hours. If both are opened together, in how many hours will the empty tank be filled?

  1. A12 hours
  2. B7.5 hours
  3. C20 hours
  4. D15 hours
Show answer
Answer: (D) 15 hours Net filling per hour = 1/10 − 1/30 = 1/15, so 15 hours.
Question 3

A can complete a work in 10 days and B can complete it in 15 days. In how many days can they complete it working together?

  1. A12.5 days
  2. B6 days
  3. C8 days
  4. D5 days
Show answer
Answer: (B) 6 days Together they do 1/10 + 1/15 = 1/6 of the work per day, so 6 days.
Question 4

Pipe A can fill a tank in 8 hours and pipe B can empty it in 12 hours. If both are opened together, in how many hours will the empty tank be filled?

  1. A21 hours
  2. B4 hours
  3. C4.8 hours
  4. D24 hours
Show answer
Answer: (D) 24 hours Net filling per hour = 1/8 − 1/12 = 1/24, so 24 hours.
Question 5

A can complete a work in 10 days and B can complete it in 40 days. In how many days can they complete it working together?

  1. A12 days
  2. B8 days
  3. C10 days
  4. D7 days
Show answer
Answer: (B) 8 days Together they do 1/10 + 1/40 = 1/8 of the work per day, so 8 days.
Question 6

Pipe A can fill a tank in 6 hours and pipe B can empty it in 10 hours. If both are opened together, in how many hours will the empty tank be filled?

  1. A12 hours
  2. B4 hours
  3. C3.75 hours
  4. D15 hours
Show answer
Answer: (D) 15 hours Net filling per hour = 1/6 − 1/10 = 1/15, so 15 hours.
Question 7

A can complete a work in 15 days and B can complete it in 30 days. In how many days can they complete it working together?

  1. A9 days
  2. B10 days
  3. C14 days
  4. D12 days
Show answer
Answer: (B) 10 days Together they do 1/15 + 1/30 = 1/10 of the work per day, so 10 days.
Question 8

Pipe A can fill a tank in 10 hours and pipe B can empty it in 15 hours. If both are opened together, in how many hours will the empty tank be filled?

  1. A27 hours
  2. B35 hours
  3. C5 hours
  4. D30 hours
Show answer
Answer: (D) 30 hours Net filling per hour = 1/10 − 1/15 = 1/30, so 30 hours.
Question 9

A can complete a work in 21 days and B can complete it in 42 days. In how many days can they complete it working together?

  1. A14 days
  2. B16 days
  3. C18 days
  4. D13 days
Show answer
Answer: (A) 14 days Together they do 1/21 + 1/42 = 1/14 of the work per day, so 14 days.
Question 10

Pipe A can fill a tank in 12 hours and pipe B can empty it in 20 hours. If both are opened together, in how many hours will the empty tank be filled?

  1. A7.5 hours
  2. B8 hours
  3. C27 hours
  4. D30 hours
Show answer
Answer: (D) 30 hours Net filling per hour = 1/12 − 1/20 = 1/30, so 30 hours.

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Question 11

A can complete a work in 6 days and B can complete it in 12 days. In how many days can they complete it working together?

  1. A9 days
  2. B4 days
  3. C6 days
  4. D8 days
Show answer
Answer: (B) 4 days Together they do 1/6 + 1/12 = 1/4 of the work per day, so 4 days.
Question 12

A can complete a work in 30 days and B can complete it in 60 days. In how many days can they complete it working together?

  1. A24 days
  2. B20 days
  3. C22 days
  4. D19 days
Show answer
Answer: (B) 20 days Together they do 1/30 + 1/60 = 1/20 of the work per day, so 20 days.
Question 13

A can complete a work in 24 days and B can complete it in 40 days. In how many days can they complete it working together?

  1. A14 days
  2. B19 days
  3. C15 days
  4. D17 days
Show answer
Answer: (C) 15 days Together they do 1/24 + 1/40 = 1/15 of the work per day, so 15 days.
Question 14

Pipe A can fill a tank in 9 hours and pipe B can empty it in 12 hours. If both are opened together, in how many hours will the empty tank be filled?

  1. A3 hours
  2. B36 hours
  3. C33 hours
  4. D5.1428571428571 hours
Show answer
Answer: (B) 36 hours Net filling per hour = 1/9 − 1/12 = 1/36, so 36 hours.
Question 15

Pipe A can fill a tank in 15 hours and pipe B can empty it in 20 hours. If both are opened together, in how many hours will the empty tank be filled?

  1. A8.5714285714286 hours
  2. B57 hours
  3. C60 hours
  4. D65 hours
Show answer
Answer: (C) 60 hours Net filling per hour = 1/15 − 1/20 = 1/60, so 60 hours.
Question 16

A can complete a work in 18 days and B can complete it in 36 days. In how many days can they complete it working together?

  1. A12 days
  2. B14 days
  3. C11 days
  4. D27 days
Show answer
Answer: (A) 12 days Together they do 1/18 + 1/36 = 1/12 of the work per day, so 12 days.
Question 17

A can complete a work in 40 days and B can complete it in 60 days. In how many days can they complete it working together?

  1. A50 days
  2. B23 days
  3. C26 days
  4. D24 days
Show answer
Answer: (D) 24 days Together they do 1/40 + 1/60 = 1/24 of the work per day, so 24 days.

These are RankerClub practice questions written in the Delhi Police Constable pattern. They are not official SSC/IBPS/RRB papers.

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