Answer
the number of gallons of water used in a shower lasting 11 minutes is 66 gallons.
Work Step by Step
Consider the proportional relation between the number of gallons of water used in a shower and the time taken in shower.
Because, the shower lasting 5 minutes uses 30 gallons of water.
So, the shower lasting 1 minute will use $\frac{30}{5}\ \text{gallons}$of water.
This shows that the shower lasting 11 minutes uses $\left( \frac{30}{5}\times 11 \right)\ \text{gallons}$of water. It is solved as,
$\begin{align}
& W=\frac{30}{5}\times 11 \\
& =66\ \text{gallons}
\end{align}$
Hence, the number of gallons of water used in a shower lasting 11 minutes is 66 gallons.
