Calculus
posted by Anonymous .
Air is being pumped into a spherical balloon and the volume is increasing at the rate of 100 cubic cm per minute. How fast is the radius of the balloon increasing when the radius is 10 cm?
(V=4/3 times pie times r^3)

V = (4/3)πr^3
dV/dt = 4πr^2 dr/dt
100 = 4π(100) dr/dt
dr/dt = 1/(4π) cm/min