Answer:
[tex]2827.4 \dfrac{ft}{s}[/tex]
Step-by-step explanation:
[tex] A = \pi r^2 [/tex]
[tex] \dfrac{dA}{dt} = 2 \pi r \dfrac{dr}{dt} [/tex]
[tex] \dfrac{dA}{dt} = 2 \times \pi \times 30~ft \times 15 \dfrac{ft}{s} [/tex]
[tex] \dfrac{dA}{dt} = 2827.4 \dfrac{ft}{s} [/tex]