Question

15. A tank has three pipes, two of which can fill the
tank in 9 minutes and 12 minutes when opened
separately. The third pipe can alone empty the full
tank in 6 minutes. If all three pipes are opened
together, how many minutes will it take for an
empty tank to be filled?​

Answer 1

Step-by-step explanation:

9 minutes=1/9th work in 1 min

12 minutes=1/12th work in 1 min

6 minutes=1/6th work in 1 min

According to the question:

1/9+1/12+1/6=4+3+6/36=13/36

or, 13/36=36/13min