Pipes And Cisterns Q28

28.	A tank is filled in 5 hours by three pipes A, B and C. The pipe C is twice as fast as B and B is twice as fast as A. How much time will pipe A alone take to fill the tank?
	A. 20 hours B. 25 hours C. 35 hours D. Cannot be determined E. None of these

Answer: Option C

Explanation:

Suppose pipe A alone takes x hours to fill the tank.

Then, pipes B and C will take	x	and	x	hours respectively to fill the tank.
	2		4

	1	+	2	+	4	=	1
	x		x		x		5

	7	=	1
	x		5

                     x = 35 hrs.