A and B can do a piece of work in 10 days and 15 days, respectively. They worked together, but 5 days before the completion of the work, A left. In how many days was the work completed?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 9.
Given that
A and B can do a piece of work in 10 days and 15 days, respectively.
Total work = LCM (10, 15) = 30
The efficiency of A = 30/10 = 3
The efficiency of B = 30/15 = 2
Let Work is completed in D days
According to the question
⇒ A × (D - 5) + B × D = 30
⇒ 3 × (D - 5) + 2 × D = 30
⇒ 3D + 2D = 30 + 15 = 45
⇒ 5D = 45
⇒ D = 9 days