P completes a work in 12 days and Q in 24 days. In how many days P and Q working together can complete the same work?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 8 days.
Let the total work to be done (LCM of 12 and 24) be 24 units.
According to the question,
Efficiency of P = 24/12 = 2 units/day
Efficiency of Q = 24/24 = 1 unit/day
Time taken by both of them to complete the work = 24/(2 + 1)
⇒ 24/3 = 8 days