P and Q can complete a project in 15 days and 10 days, respectively. They started doing the work together, but after 2 days, Q had to leave and P alone completed the remaining work. In how many days was the whole work completed?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2. i.e. 12 .
According to question,
(P + Q)'s 1 day's work = 1/15 + 1/10
⇒ (2 + 3)/30
⇒ 5/30
⇒ 1/6
Work done by P and Q in 2 days = 1/6 × 2
⇒ 1/3
Remaining work = 1 - 1/3
⇒ 2/3
Now,
1/15 work is done by P in 1 day.
So, 2/3 work will be done by P in 15 × 2/3 = 10 days
So, the total time is taken = 10 + 2
⇒ 12 days