Answer:
9/2π cm/s
Explanation:
Volume of the spherical balloon V= 4/3πr³
Rate of change of volume dV/dt = dV/dr * dr/dt
dV/dr = 3(4/3πr²)
dV/dr = 4πr²
dV/dr = 4π(2)²
dV/dr = 16π
If V = 72cm²/s
72 = 16π*dr/dt
dr/dt = 72/16π
dr/dt = 9/2π cm/s
Hence the radius is changing at 9/2π cm/s