幫我計數OK??(Thx)

幫我計以下的問題:
1)The volume of a cylinder is V.If the base radius is doubled and the height is unchangad.Find the volume of the new cylinder.


A. 2V
B. 4V
C. 8V
D. 9V
E. 16V


2) A sphere is inflated with air.If the surface area of the sphere is increased by 21%, what is the percentage change of its volume?

A. increase 10%
B. increase 21%
C. increase 33.1%
D. decrease 21%
E. decrease 33.1%



3)The figure shows a cylinder with baseradius 4 cm.The cylinder contains water with height h cm.A sphere with radius 4cm is immersed(浸入) into the cylinder,the water just covers the sphere.Find the value of h.

A. 2 cm
B. 3 cm
C. 2/3 cm
D. 4/3 cm
E. 8/3 cm



4) The vertical angle of a right cone is 60 °.If the curved surface
area of the cone is72πcm(square),find the volume of the cone.


A. 72√3πcm(cube)
B. 1443πcm(cube)
C. 144√3 πcm(cube)
D. 216√3πcm(cube)
E. 432πcm(cube)