A right circular cylinder has a base of radius $3$ and height $6.5$. What is its volume?

The volume of a right circular cylinder is $V = \pi r^{2} h$. With $r = 3$ and $h = 6.5$: $V = \pi (3^{2})(6.5) = \pi (9)(6.5) = 58.5 \pi$. - Trap A ($19.5 \pi = \pi \cdot 3 \cdot 6.5$) uses $r$ instead of $r^{2}$. - Trap B ($39 \pi = 2 \pi \cdot 3 \cdot 6.5$) is the **lateral surface area** (the side, $2 \pi r h$), not the volume. - Trap D ($117 \pi$) doubles the correct answer. Load-bearing detail: the *area of the base* is $\pi r^{2}$, not $2 \pi r$. Multiplying by $h$ then gives the volume.