Area and Perimeter: math test solutions, Grade 3 – download the PDF

1 Tiles and rows / 3 pts

(a) \(6 \times 8 = 48\). The kitchen floor has an area of 48 square feet. (2 pts)

(b) The pantry: \(9 \times 5 = 45\) square feet. \(48 - 45 = 3\). The kitchen floor is greater by 3 square feet. (1 pt)

2 Rectangle measures / 4 pts

(a) Area: \(11 \times 8 = 88\) square meters. (1 pt) Perimeter: \(2 \times (11 + 8) = 38\) meters. (1 pt)

(b) Width: \(72 \div 9 = 8\) inches. (1 pt) Perimeter: \(2 \times (9 + 8) = 34\) inches. (1 pt)

3 Break it apart / 4 pts

(a) \(6 \times 7 = 42\) square feet and \(3 \times 7 = 21\) square feet. (2 pts)

(b) \(42 + 21 = 63\). The area of the mural is 63 square feet. (1 pt)

(c) She used the distributive property: \(7 \times (6 + 3) = 7 \times 6 + 7 \times 3\). (1 pt)

4 Around the polygon / 3 pts

(a) \(5 + 8 + 6 + 9 + 4 = 32\). The perimeter is 32 centimeters. (1 pt)

(b) \(10 + 8 = 18\) (1 pt), then \(27 - 18 = 9\). The third side is 9 inches. (1 pt)

5 Same area / 3 pts

(a) The pairs with product 18 are 18 by 1, 9 by 2, and 6 by 3. The perimeters are \(2 \times 19 = 38\), \(2 \times 11 = 22\), and \(2 \times 9 = 18\). (2 pts)

(b) The 6 by 3 rectangle has the smallest perimeter, 18 units. (1 pt)

6 An L-shaped room / 3 pts

(a) Cut the room into a top rectangle and a bottom rectangle. The top is 4 m by 5 m: \(4 \times 5 = 20\). The bottom is 11 m by 3 m: \(11 \times 3 = 33\). Then \(20 + 33 = 53\). The area is 53 square meters. (2 pts)

(b) \(4 + 5 + 7 + 3 + 11 + 8 = 38\). The perimeter is 38 meters. (1 pt)