Q: X can finish a work in 21 days. Y can finish the same work in 15 days. Y worked for 5 days and left the job. how many days does X alone need to finish the remaining work?\nOptions:\n(A) 12\n(B) 13\n(C) 16\n(D) 14\n(E) 18 Let's give some random thoughts before answering.
User
Work done by X in 1 day = 1/21\nWork done by Y in 1 day = 1/15\nWork done by Y in 5 days = 5/15 = 1/3\nRemaining work = 1 – 1/3 = 2/3\nNumber of days in which X can finish the remaining work = (2/3) / (1/21) = 14
Therefore, the answer is (D).
Assistant