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**dcfi6052** Water is poured into a conical funnel at a rate of 1 cm'3/s. The radius of the top of the funnel is 10cm and the height of the funnel is 20cm. Find the rate at which the water level is rising when it is 5cm from the top of the funnel.

Formula for volume of a cone, V=1/3 pi r'2h

I did a diagram, found out what I have to find and what I am given, and I believe I know the rest of the steps but am not sure. My question is do you sub the 10cm for r and 20cm for h in the volume equation given, take the derivative of that, then use the chain rule to work out the equation?

If so, could you show and explain how do do those steps up to the derivative. (I can work out the rest from there)

If your really feeling generous you could find out the final answer, just so I know I'm on the right track for the rest of the question.

Thx in advance for the help.