A tank is filled by 3 pipes A,B,C in 8 hours. Pipe C is twice as fast as B and B is twice as fast as A. How much will pipe A alone take to fill the tank ? Select: A) 25hr B) 35hr C) 56hr D) 20hr E) 50hr
Suppose pipe A alone take x hours to fill the tank   Then pipe B and C will take x/2 and x/4 hours respectively to fill the tank.   1/x + 2/x + 4/x = 1/8   7/x = 1/8   x = 56 hours   Answer is 56hr
<result>C</result>
A tank is filled by 3 pipes A,B,C in 8 hours. Pipe C is twice as fast as B and B is twice as fast as A. How much will pipe A alone take to fill the tank ?