As Khalid inflates a spherical balloon, Kareem wonders about its different rates. He knows that the rate at which Khalid blows is equal to the rate at which the volume changes . As the balloon inflates, other aspects are changing as well, such as the radius and the surface area. Homework Help ✎

1. If = 10, find the rate of change of the radius, , when r = 3 cm.

2. If = 12, find the rate of change of the surface area, , when r = 5 cm.

3. Describe what happens to the balloon when is negative.