Question

Gas is escaping from a spherical balloon at the rate of 2 ft3 per min. How fast is the radius shrinking
when the radius is 12 ft?

Answer 1

So they told us that the rate of change of the volume, \(\Large \dfrac{dV}{dt}=-2ft^3/min\)
And they want us to find the rate of change of the radius, \(\Large \dfrac{dr}{dt}=?\)
when \(\Large r=12ft\)

Answer 2

So we need to start with the formula for a sphere, remember that one?