Question

James can do a piece of work in 25 days and Kishan can finish it in 20 days. They work together for 5 days and then James leaves. In how many days will Kishan finish the remaining work?

• A. 10 days
• B. 11 days
• C. 12 days
• D. 13 days

Answer 1

The correct option is B

11 days

Time taken by James (say J) to finish the work = 25 days

J’s 1 day’s work = $\frac{1}{25}$

Time taken by Kishan (say K) to finish the work = 20 days

K’s 1 day’s work = $\frac{1}{20}$

(J + K)’s 1 day’s work = $\frac{1}{25}$ + $\frac{1}{20}$ = $\frac{9}{100}$

(J + K)’s 5 day’s work = $\frac{9\times 5}{100}$ = $\frac{9}{20}$

Remaining work = 1 - $\frac{9}{20}$ = $\frac{11}{20}$

Now, $\frac{1}{20}$ work is done by K in 1 day

Therefore, $\frac{11}{20}$ work will be done by K in $\frac{11\times 20}{20}$ days = 11 days