7th Grade Math

Lesson 2B Surface Area 585

Find the surface area of each rectangular prism. Round to the nearest tenth

if necessary.

Examples 1 and 2

1.

3 ft

4 ft

6 ft

2.

3.4 cm

8.2 cm

5.5 cm

Example 3 3. GIFTS Marsha is wrapping a gift. She places it in a box 8 inches long,

2 inches wide, and 11 inches high. If Marsha bought a roll of wrapping

paper that is 1 foot wide and 2 feet long, did she buy enough paper to

wrap the gift? Justify your answer.

Example 4 4. INSULATION The attic shown is a

triangular prism. Insulation will be

15 ft

15 ft

3 0 ft

21.2 ft

placed inside all walls, not including

the floor. Find the surface area that

will be covered with insulation.

= Step-by-Step Solutions begin on page R1.

Extra Practice begins on page EP2.

Find the surface area of each rectangular prism. Round to the nearest tenth

if necessary.

Examples 1 and 2

5.

8 cm

5 cm

9 cm

6.

13 m

5 m

4 m

77

8.5 mm

15 mm

12.3 mm

8. 
   

   (^) 12 ft
   1.7 ft
   6.4 ft

   
   


9. 
   

   3 in.
   4 in.^34 6 in.^1
   4

   
   


10. 
    

    8 yd^13
    12 yd^12
    10 yd^56
    Example 3 11. BOOKS When making a book cover, Anwar adds an additional 20 square
    inches to the surface area to allow for overlap. How many square inches
    of paper will Anwar use to make a book cover for a book 11 inches long,
    8 inches wide, and 1 inch high?

    
    


11. 
    

    FENCES If one gallon of paint
    covers 350 square feet, will
    8 gallons of paint be enough
    to paint the inside and outside
    of the fence shown once? Explain.

    
    

60 ft

6 ft

45 ft

580_591_C10_L2_895130.indd 585 1/4/10 2:42 PM