Question

A pipe can fill a cistern in 12 minutes while a second pipe fills it in 15 minutes. But a third pipe can empty that completely filled cistern 16 minutes. The first two pipes are kept open for 5 minutes initially and then the third one is also opened. Then the further time (in minutes) taken to empty that cistern is

Answer 1

Answer:

Step-by-step explanation:

the filled part is 5(1/12 + 1/15)=3/4

let X be time taken to empty the tank..

so,

X(1/6)=3/4

X=9/2 mins...

X=4mins 30 secs

Hope it helps you..