15 men take 21 days of 8 hrs. each to do a piece of work. How many days of 2 hrs. each would it take for 21 women if 3 women do as much work as 2 men? Choices.
A) 30  B) 20  C) 40  D) 60  E) 90

Rationale: "let 1 man does 1 unit / hr of work 15 m in 21 days of 8 hrs will do ( 15 * 21 * 8 ) units 3 w = 2 m 1 w = ( 2 / 3 ) units / hr 21 w with 2 hrs a day will take ( 15 * 21 * 8 ) / ( 21 * 2 * ( 2 / 3 ) ) days = > 90 days answer : e"
Answer: E