A balloon is being filled with air, and its volume $V$ after $t$ minutes is given by $V=4t^2$, where $V$ is measured in liters. Draw the graph of the function and the secant line passing through $A$ and $B$. The endpoints of the interval $1\leq{t}\leq{3}$ correspond to $A$ and $B$. Then, calculate the slope of the secant line and interpret it in terms of an average rate of change over the interval.

• A. $16~\text{L/min}$, The balloon's volume increases by $16~\text{L/min}$ on average.
• B. $-16~\text{L/min}$, The balloon's volume decreases by $16~\text{L/min}$ on average.
• C. $8~\text{L/min}$, The balloon's volume increases by $8~\text{L/min}$ on average.$-16~\text{L/min}$
• D. $-8~\text{L/min}$, The balloon's volume decreases by $8~\text{L/min}$ on average.

Answer: (A)