Question

A can do a piece of work in 25 days and B in 20 days. They work together for 5 days and then A goes away. In how many days will B finish the remaining work ?

• A. 17 days
• B. 11 days
• C. 10 days
• D. 15 days

Answer 1

The Correct Option is B

To solve this problem, we need to calculate the combined work of A and B for 5 days, then determine how many more days B will need to finish the remaining work alone.

First, calculate the work done by each in one day:

• A can complete the task in 25 days, so A's one day work = 1/25.
• B can complete the task in 20 days, so B's one day work = 1/20.

Next, calculate their combined work for one day:

Combined work of A and B in one day = 1/25 + 1/20

= (4 + 5) / 100

= 9/100.

Now, calculate the work done by both in 5 days:

Work done in 5 days = 5 * 9/100 = 45/100 = 9/20.

The remaining work = Total work - Work done in 5 days

Remaining work = 1 - 9/20 = 11/20.

Finally, find out how many more days B, working alone, will take to complete the remaining work:

Since B's one day work = 1/20, the time taken by B to complete 11/20 work = (11/20) / (1/20) = 11.

Therefore, B will take 11 days to finish the remaining work.