7th Grade Math

Test PracticeT

Lesson 2B Surface Area 587

C 22. REASONING The bottom and sides of a pool in the shape of a rectangular

prism will be painted blue. The length, width, and height of the pool

are 18 feet, 12 feet, and 6 feet, respectively. Explain why the number

of square feet to be painted is not equivalent to the expression

2(18)(12) + 2(18)(6) + 2(12)(6).

23. REASONING Determine if the following statement is true or false. Explain
    your reasoning.
    If you double one of the dimensions of a rectangular prism,
    the surface area will double.


24. CHALLENGE The figure at the right is made by 12 cm
    12 cm

15 cm

15 cm

placing a cube with 12-centimeter sides on top

of another cube with 15-centimeter sides.

Find the surface area.

25. E WRITE MATH Explain why the surface area
    of a three-dimensional figure is measured in
    square units rather than in cubic units.

Find the volume of each cone. Round to the nearest tenth. (Lesson 1F)

28.

24 cm

22 cm

29. 10.4 yd

3.1 yd

30. LANDSCAPING Pat is digging circular post holes for a new fence. It is
    recommended that the holes are at least 10 inches across and 18 inches
    deep. What is the least amount of dirt she is removing for each hole? Round
    to the nearest tenth. (Lesson 1D)


31. Which of the following expressions
    represents the surface area of a cube
    with side length w?
    A. w^3
    B. 6 w^2
    C. 6 w^3
    D. 2 w + 4 w^2


32. How much cardboard is needed to make
    the box shown?
    F. 37.5 ft^2

2.5 ft

1.6 ft

2 ft

G. 24.4 ft^2

H. 8 ft^2

I. 6.1 ft^2

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