P and Q together can do a job in 15 days. P is thrice as efficient as Q. In how many days can P alone do the job?

Question

Question

This question was previously asked in

SSC GD Constable (2022) Official Paper (Held On : 30 Jan 2023 Shift 1)

Answer 1

Given:

P and Q can do a job in 15 days, P is 3 times as efficient as Q.

Concept:

Work done is directly proportional to efficiency.

Solution:

If Q's efficiency is q, then P's efficiency is 3q.

(P + Q)'s 1 day's work = (3q + q) = 4q = 1/15

Then, q = 1/60.

P's 1 day's work = 3q = 3/60 = 1/20.

Therefore, P can complete the job alone in 20 days.