1, the radius ratio of cylinder and cone is 2:3, then the area ratio is 4: 9, and the volume ratio of cylinder and cone is (4 * 3): (9 * 2/3) = 2: 1.

2. The radius of the bottom surface of the cone is constant, and the volume will increase by 2 times if the height is increased by 2 times;

If the height of the cone is constant, the radius of the bottom surface is enlarged by 2 times and the area of the bottom surface is enlarged by 4 times, then the volume is 4 times.

3, 48.