7th Grade Math

Chapter Study Guide and Review 613

Volume (continued)

Volume of Pyramids (Lesson 1E)

Find the volume of each pyramid. Round to

the nearest tenth.

17.

4.7 mm

2 mm 2 mm

18.

2 ft

4 ft

6 ft

19. CRYSTALS Jess bought a pyramid-shaped
    crystal to hang in her room. The
    rectangular base of the crystal measures
    9 centimeters by 8 centimeters and has a
    height of 12 centimeters. What is the
    volume of the pyramid-shaped
    crystal?

EXAMPLE 3 Guilia bought a lawn

decoration shaped like the pyramid

shown below. Find the volume of the

pyramid-shaped decoration. Round to the

nearest tenth.

5 ft

8 ft

6 ft

V = _^13 Bh Volume of a pyramid

V = _ 31 (6 × 5) × 8 Replace B with 6 × 5 and h with 8.

V = 80 Multiply.

The volume of the pyramid-shaped lawn

decoration is 80 cubic feet.

Volume of Cones (Lesson 1F)

Find the volume of each cone. Round to the

nearest tenth.

20. 5 yd

8 yd

21. 6 in.

10 in.

22. CONTAINER Mr. Corwin built a
    cone-shaped storage container with a
    base 15 inches in diameter and a height
    of 8 inches. What is the volume of the
    container? Round to the nearest tenth.

EXAMPLE 4 Find the volume of the

cone. Round to the nearest tenth.

6 m

12 m

V = _^1

3

πr^2 h Volume of a cone

V = _^1

3

π 62 (12) Replace r with 6 and h with 12.

V ≈ 452.4 Simplify.

The volume of the cone is 452.4 cubic

meters.

Lesson 1

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