A and B can do a work in 12 days and 18 days, respectively. They worked for 4 days after which B was replaced by C and the remaining work was completed by A and C in the next 4 days. In how many days will C alone complete 50% of the same work?

Answer: Option B

Solution

Answer: Option B

Solution:

4 day work = 5 × 4 = 20
Remaining work = 36 - 20 = 16
(A + C) complete in 4 days
A + C $$\to \frac{16}{4}=4$$
3 + C = 4
C = 1
50% of work = $$\frac{36}{2}$$ = 18
C do = $$\frac{18}{1}$$ = 18 days