A bathtub is filled with water to a depth of 9 inches, At time t=0, the plug is pulled out and the water begins to run out of the tub. The depth,h(t) in inches, is decreasing at a rate given by
( d h(t))/dt = - (1/pi) sqr root h(t) (with t in seconds).
use seperation of variables to get a formula for the solution of this differential equation.
How long does it take for all but a drop or two of the water to run out of tub?