Air is pumped into a spherical balloon at the rate of 20cm^3/s^-1.find the rate of change of radius of the balloon when the radius is 6cm

Answer 1

V = (4/3)π r^3
dV/dt = 4π r^2 dr/dt

20 = 4π (36) dr/dt
dr/dt = 20/(144π) cm/s
= 5/(36π) cm/s