A tank is half full. Pipe X can fill the whole tank in 16 minutes and pipe Y can empty the whole tank in 24 minutes. If both are opened now, in how many minutes will the tank be full?

Explanation

1. 01

   Net fill rate = $\frac{1}{16} - \frac{1}{24} = \frac{3-2}{48} = \frac{1}{48}$ per minute.

2. 02

   Only half the tank needs filling: $\frac{1}{2} \times 48 = 24$ minutes.