Hakeem S. answered 11/18/19
Your Math and Physics Tutor
The volume formula that's given is V = .5πh2(18-h), the volume's rate of change is dV/dt = 3cm3/sec, and you're finding the rate of increase of the water level (dh/dt) at h = 3cm.
The first thing you can do is take the derivative of the left and right side of the volume formula with respect to time. Once that's done you'll input all known values leaving one unknown (dh/dt), solve for dh/dt and you'll have your solution.
Hope this sparks some ideas!