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February 1, 2015

February 1, 2015

Posted by **jeremy** on Wednesday, February 27, 2013 at 12:18am.

Here are the steps and reasoning I took, however arrived at an incorrect answer.

so the derivative of the volume of a cone is:

dv/dt = 1/3π(2rh dr/dt + r^2 dh/dt)

I know r = 11 and since the base diameter doesn't change, dr/dt = 0 so I can ignore the first term in the parentheses.

so dv/dt = 1/3π * r^2 dh/dt

substituting gives:

40 = 1/3π * 121 dh/dt

dh/dt = 0.3156

but the answer is 0.1052

Can someone explain what was wrong with my reasoning?

- math -
**jeremy**, Wednesday, February 27, 2013 at 1:15amNever mind, I guess I misinterpreted the problem because the radius actually does change

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