A can complete some work in 35 days and B can complete the same work in 15 days. They worked together for 8 days, then B left work. In how many days will A alone complete 60% of the remaining work?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 5.
Time taken by A to complete the whole work = 35 days
Time taken by B to complete the whole work = 15 days
Hence total work = LCM of (35 and 15) = 105 units
Now,
Efficiency of A = 105/35 = 3 units
Efficiency of B =105/15 = 7 units
They work together for 8 days,
thus work done in 8 days = Combined efficiency of A and B × 8
⇒ (3 + 7) × 8 = 80 units
Now work left after 8 days = 105 - 80 = 25 units
Time taken by A to complete 60% of remaining work = (60/100 × 25)/3 = 15/3 = 5 days