Question 277022
A faucet can fill a sink in 5 minutes. It takes twice that long for the drain to empty the sink. How long will it take to fill the sink if the drain is open and the faucet is on?

faucet can fill in 5 minutes

1/5th of sink fills in 1 minute

sink drains in 10 minutes

1/10th sink will drain in 1 minute

effective filling will be 1/5 -1/10 = 1/10 per minute

So the sink will fill in 10 minutes.