### Home > APCALC > Chapter 7 > Lesson 7.1.5 > Problem 7-49

7-49.

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

If

, calculate the rate of change of the radius, , when cm.Using just geometry (no Calculus), find the equation for a generic spherical balloon.

Substitute the given information and solve.

If

= , calculate the rate of change of the surface area, , when cm.Using just geometry, write the equation for the Surface Area of a generic spherical balloon:

Describe is happening to the balloon when

is negative. What does a negative rate represent?