Multiple choice

20 young boys can do a particular work in 12 days, while the same can be completed by 15 experienced men in 10 days. What is the ratio of efficiency of a man to that of a young boy?

  1. 6 : 5

  2. 8 : 5

  3. 7 : 4

  4. 9 : 4

  5. 3 : 2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

20 boys * 12 days = 240 boy-days. 15 men * 10 days = 150 man-days. Since the work is the same, 150 men = 240 boys, so 1 man = 240/150 boys = 1.6 boys = 8/5 boys. The ratio of efficiency (man to boy) is 8:5.

AI explanation

Using the constant work equation, the total work is the product of the number of workers and their time, so 20 boys times 12 days equals 15 men times 10 days. This gives 240 boy-days equals 150 man-days. The ratio of efficiency of a man to a boy is the inverse of their time taken for the same unit of work, which is 240 to 150. Simplifying this ratio gives 8 to 5.

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