X alone can do a piece of work in 12 days and Y alone can do the same work in 6 days. In how many days will both together complete the same work?
Let total work to be done = L.C.M. (12,6) = 12 units
X alone can do the work in 12 days, => X's efficiency = $$\frac{12}{12}=1$$ unit/day
Similarly, Y's efficiency = $$\frac{12}{6}=2$$ units/day
Thus, (X+Y)'s 1 day's work = $$1+2=3$$ units/day
$$\therefore$$ Time taken by them together to finish the work = $$\frac{12}{3}=4$$ days
=> Ans - (B)
Create a FREE account and get:
