The volume of the cone V=( 1/3)πR? H

H is the height of the water surface in the cone at any moment, and r is the response radius.

H/R = 18/6，H = 3R

V=( 1/3)πR？ 3R=πR^3=πH^3/27

dv/dt=( 1/9)πH？ dH/dt=( 1/9)πH？ =( 1/9)π* 144(- 1)=- 16π(cm^3/min)

The volume of water in the cylinder u = π r 2h.

du/dt =-dv/dt = 16π(cm^3/min)

Therefore, 16π = π r 2 * DH/dt.

dh/dt= 16/r^2= 16/25=0.64cm/min