A, B and C can complete a piece of work in 24, 5 and 12 days respectively. Working together, they will complete the same work in:

Let total work = L.C.M. (24,5,12) = 120 units

A can complete the work in 24 days, => A's efficiency = $$\frac{120}{24}=5$$ units/day

Similarly, B's efficiency = $$\frac{120}{5}=24$$ units/day

and C's efficiency = $$\frac{120}{12}=10$$ units/day

Thus, working together, 1 day work of (A+B+C) = $$5+24+10=39$$ units

$$\therefore$$ Working together, they will complete the same work in = $$\frac{120}{39}$$

= $$\frac{40}{13}=3\frac{1}{13}$$ days

=> Ans - (A)