Volume of cylinder: 200.96 cubic centimeters.

The water level rose by 8 cm.

The bottom area of the water tank is 200.96/8=25. 12 cm2.

Then a cone with a base diameter of 12 cm was immersed in water, and the water level rose by 9 cm.

Volume of usable cone: 226.08 cubic centimeters.

Then the height of the cone is 226.08 * 3/(12/2 * 3.14) = 6 cm.