Answer: It will take 10 hours to fill the sink if the drain is open and the faucet is on.
Explanation:
Since we have given that
Number of minutes that a faucet can fill a sink = 5 minutes
Number of minutes that a faucet can drain the empty a sink =
![2* 5=10\ minutes](https://img.qammunity.org/2020/formulas/mathematics/high-school/672luz45ug56o764324yd5l7uqb3hqyr8n.png)
Let the number of minutes that it will take to fill the sink if the drain is open and the faucet is on be 'x'.
According to question, using "Time and Work", we get that
![(1)/(5)-(1)/(10)=(1)/(x)\\\\(2-1)/(10)=(1)/(x)\\\\(1)/(10)=(1)/(x)\\\\x=10](https://img.qammunity.org/2020/formulas/mathematics/high-school/5ilqp98mrwz8oad29vcm28ek9rsd8b87i0.png)
Hence, it will take 10 hours to fill the sink if the drain is open and the faucet is on.