Question

if 2taps can fill a tank in 6hrs & 9hrs and the third tap can empty it in 12 hrs. How long will it take to fill the if all the taps are opened together

Answer 1

it should be the answee

Answer 2

Time needed by tap 1 to fill the tank = 6hrs
Time needed by tap 2 to fill the tank = 9hrs
Time needed by tap 3 to empty the tank = 12hrs

Therefore, total work done by all three taps in 1 hour = 1/6+1/9-1/12
=> (6+4-3)/36
=> 7/36 part

So, total time needed by all of them to fill the tank = 1/7/36
=> 36/7
=> 5 1/7 hour