Multiple choice

A job can be finished by 20 men in 30 days, working 4 hours a day. If the job was assigned to 30 men who worked for 20 days at 3 hours a day, at the end of which only one was retained, how many more days will it take for the last workman to complete the remaining work, working 10 hours a day?

  1. 20

  2. 30

  3. 40

  4. 60

  5. 45
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total work = 20 * 30 * 4 = 2400 man-hours. Work done = 30 * 20 * 3 = 1800 man-hours. Remaining work = 600 man-hours. One man working 10 hours a day takes 600 / 10 = 60 days.

AI explanation

The total work is measured as 20 men times 30 days times 4 hours, giving 2400 man-hours. The 30 men working for 20 days at 3 hours a day completes 1800 man-hours, leaving 600 man-hours of work. Using the work equivalence method, one man working 10 hours a day will need 600 divided by 10 days to finish the job, which equals 60 days.

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