A filter filled with liquid is in the shape of a vertex-down

Last updated: 7/11/2022

A filter filled with liquid is in the shape of a vertex-down cone with a height of 9 inches and a diameter of 6 inches at its open (upper) end. If the liquid drips out the bottom of the filter at the constant rate of 4 cubic inches per second, how fast is the level of the liquid dropping when the liquid is 3 inches deep?