A can do a piece of work in 15 days, which B can do in 10 days. B worked at it for 8 days. A can finish the remaining work in
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 3 days
Take the whole work as 1. B finishes it in 10 days, so B does \(\frac{1}{10}\) of it each day; the part B leaves undone is what A has to finish at A's own rate of \(\frac{1}{15}\) a day.
Work B does in 8 days \(=\displaystyle\frac{8}{10}=\frac{4}{5}\)
Work left \(=1-\displaystyle\frac{4}{5}=\frac{1}{5}\)
Time A needs \(=\displaystyle\frac{1}{5}\times15=3\) days