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Surface area of a box · 3 problems
From the 15Q20M Grade 6 workbook (Days 68–80) · Pencil, no calculator
Name:
- 1.
A box measures 9 cm by 4 cm by 2 cm. What is its surface area in square centimeters?
Answer:
- 2.
A storage bin measures 5 feet by 4 feet by 3 feet. It gets two coats of paint on the outside. What total area is painted?
Answer:
- 3.
A gift box has a length of 5 inches, a width of 4 inches, and a height of 3 inches. Mara covers every face except the top with paper. How many square inches of paper does she use?
Answer:
Answer key (for parents)
Answer key: Surface area of a box
- 1.
124
Find the three face sizes: 9 × 4 = 36, 9 × 2 = 18, and 4 × 2 = 8. Each face has a matching face, so add and double: 36 + 18 + 8 = 62, and 2 × 62 = 124 square centimeters.
- 2.
188
One coat covers the whole outside: 5 × 4 = 20, 5 × 3 = 15, 4 × 3 = 12, and 2 × (20 + 15 + 12) = 94 square feet. Two coats cover it twice: 2 × 94 = 188 square feet.
- 3.
74
The whole box would be 2 × (5 × 4 + 5 × 3 + 4 × 3) = 2 × (20 + 15 + 12) = 94 square inches. The top (5 × 4 = 20) gets no paper: 94 − 20 = 74 square inches.
Equivalent answers count as correct: 2/4 for 1/2, 0.5 for 1/2, and so on.
For parents
Answer key: Surface area of a box
- 1.
124
Find the three face sizes: 9 × 4 = 36, 9 × 2 = 18, and 4 × 2 = 8. Each face has a matching face, so add and double: 36 + 18 + 8 = 62, and 2 × 62 = 124 square centimeters.
- 2.
188
One coat covers the whole outside: 5 × 4 = 20, 5 × 3 = 15, 4 × 3 = 12, and 2 × (20 + 15 + 12) = 94 square feet. Two coats cover it twice: 2 × 94 = 188 square feet.
- 3.
74
The whole box would be 2 × (5 × 4 + 5 × 3 + 4 × 3) = 2 × (20 + 15 + 12) = 94 square inches. The top (5 × 4 = 20) gets no paper: 94 − 20 = 74 square inches.
Equivalent answers count as correct: 2/4 for 1/2, 0.5 for 1/2, and so on.