Question

How fast is the surface area of a spherical balloon increasing when the radius is 10 cm and the volume is
increasing at 15 cm3/sec? [7]

Answer 1

Do you know the equation for the volume of a sphere given the radius?

Answer 2

V= (4/3)[pi (r ^{3}\]

Answer 3

V = (v/3) pi r^3

Answer 4

The first one is correct.

Answer 5

So the next step is to come up with an expression of V in terms of time, and then determine how r then changes with time. Once you come up with an expression for r in terms of time, you can plug it into the equation for surface area, and you'll be set!