if the diameter is 16 feet, then the radius for the tank will have to be half that,
[tex]\bf \textit{volume of a cylinder}\\\\
V=\pi r^2 h\quad
\begin{cases}
r=radius\\
h=height\\
-----\\
r=8\\
h=12
\end{cases}\implies V=\pi \cdot 8^2\cdot 12\implies V=\stackrel{ft^3}{768\pi} [/tex]
now, that's how many ft³ of water the tank can hold, since she is filling it up at a rate of 6 ft³ per minute, namely in 1 minute 6 ft³ have gone in, then it'll be
768π/6 how many minutes it'll take.
namely, how many times does 6 go into 768π? well, 768π/6.
