A can complete a work in 9 days and B in 12 days. If they work together on it for 5 days, then the fraction of the work left is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. .
Total work = 36 (LCM of 9 and 12)
Total efficiency of A and B = 36/9 + 36/12 = 4 + 3 = 7
Total work done by A and B in 5 days = 5 × 7 = 35
Remaining fraction work = (36 - 35)/36 = 1/36
Therefore, the fraction of the work left is 1/36.