X can finish a work in 20 days. Y can finish the same work in 16 days. Y worked for 12 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 2
(B) 3
(C) 9
(D) 5
(E) 8 Now, let's think a bit. Some random thoughts:
Work done by X in 1 day = 1/20
Work done by Y in 1 day = 1/16
Work done by Y in 12 days = 12/16 = 3/4
Remaining work = 1 3/4 = 1/4
Number of days in which X can finish the remaining work = (1/4) / (1/20) = 5
The final answer: (D).