Question

2 pipes A and B can fill a tank in 20 minutes and 30 minutes respectively. Both pipes are opened. The tank will be filled in just 15 minutes, if the B is turned off after:​

Answer 1

Answer:

Step-by-step explanation:

Let total part of the tank to be filled = 1

Tap A fills the tank in 15 min and tap B in 20 min.

In one min, the part of tank filled by A and B will be (1/15) and (1/20) respectively.

Both the pipes are opened together for 4 minutes.

Part of the tank filled by A and B = 4 [ (1/15) + (1/20)] =7/15

After 4 minutes, pipe A is turned off

Part to be filled by B alone= 1–(7/15) = 8/15

Time taken by B = (8/15)/(1/20) = 32/3 min

Total time = 4+ (32/3) = 44/3 = 14.667 min

Ans: Total time required to fill the tank = 14.667 min