Question: A, B and C can do a piece of work in 7 days, 14 days and 28 days respectively. How long will they take to finish the work, if all the three work together?
Options:
(A) 4
(B) 9
(C) 2
(D) 11
(E) None Let's think first. Some random reasoning:
1/7 + 1/14 + 1/28 = 7/28 = 1/4
All three can finish the work in 4 days The final answer: (A).