A, B and C can complete a piece of work in 24, 6 and 12 days respectively. Working together, they will complete the same work in:

A 1/24day

B 7/24day

C 3(3/7) days

D 4 days

Correct Answer: Option C

If A can do a piece of work in n days, then A's 1 day's work = 1/n

(A + B + C)'s 1 day's work = (1/24 + 1/6 + 1/12) = 7/24

So, all the three together will complete the job in 24/7 days

or, 33/7