Chain Rule Q68

68. If 36 men can do a piece of work in 25 hours, in how many hours will 15 men

do it ?

Answer:

 Let the required number of hours be x. Then,

Less men, More hours (Indirect Proportion)

15 : 36 : : 25 : x (15 x x) = (36 x 25) (36 x 25)/15 = 60

Hence, 15 men can do it in 60 hours.