The volume of an inflating spherical balloon is increasing by dV/dt=7611 in3min. How fast is the radius increasing when the radius is r=13 in?

Answer 1

V = (4/3)πr³

So, dV/dt = 4πr²(dr/dt)

7611 = 4π(13)²(dr/dt)

dr/dt = 7611 / (676π) ≈ 3.58 in/min