# Rate of change(using chain rules)

• October 15th 2008, 03:34 PM
iwonder
Rate of change(using chain rules)
The radius of a right circular cone is increasing at a rate of 5 inches per second and its height is decreasing at a rate of 4 inches per second. At what rate is the volume of the cone changing when the radius is 30 inches and the height is 50 inches?
• October 15th 2008, 03:57 PM
skeeter
take the time derivative of the cylinder volume formula ...

$V = \pi r^2 h$

remember that the product rule is required along with the chain rule.

after you find the derivative, then substitute in all that information you were given to find the value of the volume's time rate of change.
• October 15th 2008, 04:04 PM
iwonder
the answer should be 11938 right?(Nod)
• October 15th 2008, 04:41 PM
skeeter
I get $18600\pi$ $\frac{in^3}{sec}$