If 36 men can do a piece of work in 25 hours, in how many hours will 10 men do it?
Choose the correct choice from the following:  A) 76 hours  B) 66 hours  C) 57 hours  D) 90 hours  E) 18 hours
Explanation:   Let the required numbers of hours be X.   Less men, More hours (Indirect proportion)   Therefore, 10 : 36 :: 25 : X = (10 x X) = (36 x 25) = X = (36 x 25)/10 = 90.   Hence, 10 men can do it in 90 hours.   ANSWER: 90 hours
<result>D</result>
If 36 men can do a piece of work in 25 hours, in how many hours will 10 men do it?