Question

A can do a piece of work in 12 days and B in 15 days. They work together for 5 days and then B left. The number of days taken by A to finish twice the remaining work is
1. 3
2. 8
3. 6
4. 7

Answer 1

Correct Answer - Option 3 : 6

Given:

A can do a piece of work in 12 days and B in 15 days.

Calculations:

Time taken by A to complete the work = 12 days 

so part of work done in 1 day = 1/12

similarly, part of work done by B in 1 day = 1/15

work done by (A + B) in 1 day = (1/12 + 1/15) = 9/60 = 3/20

so work done by (A + B) in 5 day = 15/20 = 3/4

Remaining work = 1 - 3/4 = 1/4

Time taken by A to complete the remaining work = 12/4 = 3 days

Time taken by A to complete twice the remaining work = 6 days

∴ the correct answer is 6 days.