A can do a piece of work in 10 days. B can do it in 24 days. If C also works with them then it take only 6 days to complete the whole work. In how many days C alone can complete the whole work?

Correct Answer: 40

Explanation:

Efficiency of A = 100/10 = 10%
Efficiency of B = 100/24 = 4.16%
Efficiency of (A+B+C) = 100/6 = 16.66%
Efficiency of C = (16.66) - (10 + 4.16) = 2.5%
Number of days required by C alone to finish the work = 100/2.5 = 40 days