Question

A tank is filled by three pipes with uniform flow. The first two pipes operating simultaneously fill the tank in the same time during which the tank is filled by the third pipe alone. The second pipe fills the tank 5 hours faster than the first pipe and 4 hours slower than the third pipe. The time required by the first pipe is:
A.6 hours
B.10 hours
C.15 hours
D.30 hours

Answer 1

Answer:

C. 15 hours

Step-by-step explanation:

First pipe alone can fill the tank in x hours

Second pipe can fill the tank in (x-5) hours

Third pipe can fill the tank in (x-5)-4 = (x-9) hours

Part filled by first pipe and second pipe together in 1 hr = part filled by third pipe in 1 hr

(1/x) + (1/x-5) = (1/x-9)

By solving the above equation we get

(X-15) * (x-3) = 0

So X = 15 or 3

We cannot take the value of x = 3

Because 3rd pipe can fill the tank in (x-9) hrs becomes negative which is not possible  

X = 15 hrs