## Task 3 - 320713

A water tank is to be filled through two pipes. To fill it using only the first pipe would take 3 hours, and to fill it using only the second pipe would take 2 hours.

In how many minutes will the tank be full if both pipes are used simultaneously?
In one minute, because $3 \mathrm{~h}=180 \mathrm{~min}$, the first pipe fills $\frac{1}{180}$ of the container, and similarly, because $2 \mathrm{~h}=120$ min, the second pipe fills $\frac{1}{120}$ of the container. Therefore, both pipes together fill

$$
\frac{1}{180}+\frac{1}{120}=\frac{1}{72}
$$

of the container in one minute. Hence, the container is filled by both pipes in 72 minutes.