Question

A bathtub can be filled in 8 min. it takes 12 min for the bathtub to drain. if the faucet is turned on but the drain is also left open, how long will it take to fill the tub?

Answer 1

Time taken to fill the bathtub is 8 min
time taken to drain the bathtub is 12 min
fraction of bathtub filled in 1 hour=1/8
fraction of bathtub drained in 1 hour=1/12
fraction that will be filled in a minute given that both taps are opened at he same time:
1/8-1/12
=1/24
thus time taken for the bathtub to be filled is 24 min