Question

an inlet pipe can fill a water tank in 10 hours while and outlet pipe can empty the same tank in 15 hours.by mistake both the pipes are left open. how long will it take to fill the water tank

Answer 1

When both the pipes are open together, let the time taken be x hrs

1/x=(1/10)+(1/15)
1/x=(3+2)/30
1/x=5/30
1/x=1/6
x=6hrs

Answer 2

Answer:

Time taken to fill the tank when both the taps open be xhrs

In 1hour the tank is filled when both the taps open=1/x

In 10hrs the tank is filled.

So, in 1hr the tank filled=1/10

In 15hrs the tank is emptied.

So, in 1hr the tank emptied=1/15

A.T.Q

1/X = 1/10 - 1/15

= (3-2)/30

=1/30

So x=30hrs