Question

A pipe can fill a tank in 1/5
hour and another pipe
in 1/4 hour, but a third pipe can empty it in
10
hour. The first two pipes are kept open for 5
minutes and then the third pipe is also opened.
In what time is the tank emptied.​

Answer 1

Answer:

first of all there is a correction in question it should be it can empty it in 10 minutes not 10 hours

explanation

pipe a can fill tank in 1/5 of hr which 12 minutes.

pipe b can fill it in 1/4 of hour which is 15 minutes

1 minute work of

pipe a = 1/12

pipe b = 1/15

total 1 minute work of both

1/12 +1/15 = 3/20

5 minute work of a and b

3/20 *5 =3/4

it means 3/4 of tank is filled now pipe c has to empty it

pipe c can empty tank in 10 min

1 min work 1/10

time take to empty 3/4 of tank

1/10 ÷ 3/4

1/10 *4/3

2/15 answer