Need help very quickly!

Question

1.) Identify the volume of the hemisphere in terms of π.

A.) V = 121.5π cm³

B.) V = 486π cm³

C.) V = 364.5π cm³

D.) V = 729π cm³

2.) Identify the volume and surface area of the hemisphere in terms of π.

A.) V = 7776π in³; S = 972π in²

B.) V = 7776π in³; S = 1296π in²

C.) V = 3888π in³; S = 972π in²

D.) V = 3888π in³; S = 1296π in²

3.) Find the volume and surface area of the composite figure. Give four answer in terms of π.

A.) V ≈ 53.3π in³; S = 60π in²

B.) V = 60π in³; S ≈ 53.3π in²

C.) V = 54π in^3; S = 56π in²

D.) V = 56π in³; S = 54π in²

Need help very fast! Please give explanation and the answer.

Answer 1

1. Volume of a sphere is 4/3 * PI * R^3. In this problem, radius (R) = 9. Plug that into formula to get volume of whole sphere, then divide that by two to get volume of hemisphere.
2. Here radius = 18. Plug radius into volume equation to get volume of whole sphere, then divide that by two to get volume of hemisphere. Surface area of a sphere is 4*PI*R^2. Plug radius into surface area equation to get surface area of whole sphere, then divide that by two to get surface area of hemisphere.
3. That figure can be broken down into a cylinder and a hemisphere. Find the volume and surface area of each then add together. The volume and surface area of a hemisphere are computed as for problem 2. Notice that for the hemisphere the diameter is 4 cm, so the radius is 2 cm. The volume of a cylinder is PI*R^2*Height and the surface area of a cylinder is 2*PI*Radius*(Height+Radius). The radius of the cylinder is the same as the radius of the hemisphere and the height of the cylinder is given as 12 cm. Plug those values into the equations for the cylinder.