A man is twice as fast as a woman and a woman is twice as fast as a boy. If together, they can finish a work in 15 days, how long will a boy take alone to finish the same work?
Answer & explanation
Correct answer: option 2
Man : Woman : Boy
Efficiency 4 : 2 : 1
Total efficiency = 4 + 2 + 1 = 7
Total work = efficiency x No. of days = 7 x 15 = 105
Time taken by a boy to complete this same work = \(\frac{Total\; work}{efficiency}\)
= \(\frac{105}{1}\) = 105 days