Volume = 1/3 bottom area * height = 1/3πr? * Height =1/3 * 3.14 * 2 * 2 * 9 = 37.68 cubic decimeter.

2. Rotate the cylinder around the width to get 1 cylinder.

The radius is length = 5cm, and the height is width = 4cm.

Volume =πr? * Height =3. 14*5*5*4=3 15 cubic centimeter.

3. The pool surface has an inner diameter of 4m and a radius of 2m.

Volume =πr? * Height =3. 14*2*2* Height =62.8 cubic meters.

Height =5 meters

This pool is 5 meters deep.

4. Cylinder =πr? * high

Cone = 1/3πr？ * high

Equal base and equal height means equal radius.

Cone = 1/3 cylinder

If the volume difference is 4.8 cubic meters, cylinder-cone =2/3 cylinder =4.8 cubic meters.

Cylinder =7.2 cubic meters

Cone =2.4 cubic meters

5. Algorithm (1) Cone sand pile volume = 1/3 bottom area * height = 1/3*3.6*2=2.4 cubic meters.

Cuboid bunker = length * width * height =4*2* height =2.4

Height = 0.3m

Can be laid 0.3 meters thick.

Algorithm (2) lets the thickness of the energy layer be x.

Cuboid sandpit volume = conical sandpile volume

Length * width *x= 1/3 bottom area * height

4 * 2 * x =1/3 * 3.6 * 2 = 2.4 cubic meters.

X = 0.3m

Can be laid 0.3 meters thick.