Question

A faucet in a large tank can fill the tank in 12 hours. However, there is a hose in the tank which would be able to empty the tank in 18 hours. If someone left both hoses on, how long would it take to fill the tank using the faucet.

Answer 1

It would take the faucet 18 hours to fill the tank because 18/12=1.5.  That means it will be 1.5 times slower to fill the tank up with the hose on.  1.5*12=18.