A water tank has the shape of a circular cone pointed end points up. The radius of the bottom is 12ft and the height is 20ft. If water is pumped into the tank at the rate of 10pi ft^3/min, find the rate at which the water level is rising when the water is 15ft deep.

Question

anonymous · Answer

I thought I got the answer but the book's answer differs with mine.

|dw:1350350076372:dw|

Isn't the volume of the water the volume of the entire cone minus the volume of the cone of air above the water?

V = (pi/3 * 12^2 * 20) - (pi/3 * r^2 * (20 - h)) = 960pi - (pi/3 * r^2 * (20 - h))

anonymous · Answer

|dw:1350353442588:dw|