Ravi can do a piece of work in 15 days while Prakash can do it in 30 days. In how many days will they finish it together?
Options:
(A) 11 days
(B) 9 days
(C) 8 days
(D) 12 days
(E) 10 days Hmmm, my stream of consciousness:
1/15 + 1/30 = 3/30
10/1 = 10 days So, the answer is (E).