8th Grade Math

Definitions and Examples

Volume = l x w x H

Volume = ½ b x h x HH = how tall the figure is

Volume = π x r2 x HH = how tall the figure is

Volume = l x w x H ÷ 3H = how tall the figure is

Volume = π x r2 x H÷ 3H = how tall the figure is

Volume = 4/3 x π x r3

Volume = ½ b x h x H ÷ 3H = how tall the figure is

6

13

Volume = π x 62 x 13

1470.27 cubic units

6

13

12

8

7

Volume = ½ 12 x 8 x 7

336 cubic units

12

8

7

6

20 18

7

Volume = ½ 6 x 7 x 18 ÷ 3

126 cubic units

6

20 18

7

10

12

8

6

Volume = ½ 8 x (10 + 12) x 6

528 cubic units

10

12

8

6

8

5

Volume = π x 52 x 8 ÷ 3

209.44 cubic units

8

5

A camping tent has a triangular end that

measures 8 feet at the base and is 5 feet

tall. The length of the tent is 6 ½ feet.

What is the volume of the tent?

Volume = ½ 8 x 5 x 6.5

130 cubic feet

6.5

8

5

The inside of Ben’s entertainment center

measures 16 inches by 18 inches by 40

inches. Ben estimates that he needs at least

7 cubic feet to fit the new Plasma T.V. Is

there enough room to fit the T.V.?

40 x 16 x 18

11520 inches cubed, but we want cubic feet.

12 inches in a foot cubed = 1728 feet.

11520 ÷ 1728 = 6 2/3 feet cubed; not enough

room

16

18

40

A cone and a cylinder each have a diameter

of 10 cm. A prism and a pyramid each have

square bases that are 10 cm. on a side. All

of the solids have a height of 8 cm. Order

the solids according to their volume from

least to greatest.

Cone, Square Pyramid, Cylinder, Square Prism

8

510

8

5

8

8

10

10

10

π x 52 x 8 ÷ 3

209.44 10 x 10 x 8 ÷ 3

266.67

π x 52 x 8

628.32

10 x 10 x 8

800