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?
Show answer & explanation
Correct answer: B
Explanation
The Correct answer is option 2 i.e. 20 days.
P and Q together can do a job = 15 days
P is thrice as efficient as Q
So, the ratio of the efficiency of P and Q = 3x : 1x
Total work = Sum of the efficiency Efficiency × total days
Total work = (3x + x) × 15 = 60x
P alone do the job = Total work/Efficiency of P = 60x/3x = 20 days