A can do a piece of work in 40 days and B can do the same work in 80 days. They work together for 20 days, how much of the work is left to complete?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 1/4
Given that
A can do a piece of work in 40 days
B can do a piece of work in 80 days
Together, they can do a part of that work in 20 days
Total work = LCM (40, 80, and 20) = 80 days
The efficiency of A = 80/40 = 2
The efficiency of B = 80/80 = 1
According to the question
The work is done by both A and B = (2 + 1) × 20 =60
The remaining work = 80 - 60 = 20
Hence, the remaining part of work = 20/80 = 1/4