All the solutions provided inÂ **McGraw Hill My Math Grade 3 Answer Key PDF Chapter 13 Review **will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 3 Chapter 13 Review Answer Key

**Vocabulary Check**

**Use the word bank to complete each sentence.**

area

composite figure

formula

perimeter

square unit

unit square

Question 1.

The distance around the outside of a figure is its ______________.

Answer: The distance around the outside of a figure is its **perimeter**.

Question 2.

A unit square has one _______________ of area and can be used to measure area.

Answer: A unit square has one **square unit** of area and can be used to measure area.

Question 3.

A _______________ is an equation that shows the relationship between two or more quantities.

Answer: A **formula** is an equation that shows the relationship between two or more quantities.

Question 4.

_______________ is the number of square units needed to cover a figure without overlapping.

Answer: **area** is the number of square units needed to cover a figure without overlapping.

Question 5.

A square with aside length of one unit is called a _______________.

Answer: A square with aside length of one unit is called a **unit square**

Question 6.

A _______________ is made up of two or more figures.

Answer: A **composite figure** is made up of two or more figures.

**Concept Check**

**Estimate the perimeter of each figure Âˇn centimeters. Then measure the perimeter to the nearest centimeter.**

Question 7.

Estimate: _______________

Actual: _________________

Answer:

Esimated perimeter is 10.

P = 3 + 3 + 2 = 8 cm

So, the actual perimeter is 8 centimeters.

Question 8.

Estimate: _______________

Actual: _________________

Answer:

Esimated perimeter is 10.

P = 2 + 2 + 4 + 4 = 12 cm

So, the actual perimeter is 12 centimeters.

**Find the perimeter of each figure.**

Question 9.

Answer:

P = 3 + 6 + 4 = 13 cm

So, the perimeter of the given figure is 13 cm.

Question 10.

Answer:

P = 4 + 4 + 4 + 4 + 4 + 4 = 24 ft

So, the perimeter of the given figure is 24 ft.

**Algebra Find the unknown side length for each figure. The perimeter of each figure is 30 meters.**

Question 11.

The unknown is _____________ meters.

Answer:

P = 30m

L = 10m

W = x

P = 2L + 2W

30 = 2(10) + 2W

30 – 20 = 2W

2W = 10

W = 10/2 = 5 meters

Question 12.

The unknown is _____________ meters.

Answer:

P = 30m

s = 6

P = 5s

30 = 5s

s = 30/5

s = 6

So, the unknown is 6 meters.

**Algebra Count unit squares to find the area of each figure. Then write a multiplication equation.**

Question 13.

Area: _______________

Equation: ______________

Answer:

L = 5

W = 2

Area of the rectangle = lw

A = 5 Ă— 2 = 10 sq. units

Question 14.

Area: _______________

Equation: ______________

Answer:

l = 3

w = 4

Area of the rectangle = lw

A = 3 Ă— 4 = 12 sq. units

**Find the area of each rectangle.**

Question 15.

______________ square inches

Answer:

l = 6 in.

w = 4 in.

Area of the rectangle = lw

A = 6 Ă— 4 = 24 sq. in.

Question 16.

______________ square inches

Answer:

l = 9m

w = 5m

Area of the rectangle = lw

A = 9 Ă— 5 = 45 sq. meters

**Problem Solving**

Refer to the figure at the right for Exercises 17-18. The figure represents Kathleenâ€™s backyard.

Question 17.

Use the Distributive Property to find the area of Kathleenâ€™s backyard.

Answer:

l = 12m

w = 5m

Area of the rectangle = lw

A = 12 Ă— 5

= (6 Ă— 5) + (6 Ă— 5)

= 30 +30

= 60 sq. meters

Question 18.

Tile the rectangle to find its area. What do you notice?

Answer:

l = 3

w = 4

Area = 3 Ă— 4 = 12 sq. units

**For Exercises 19 through 21, refer to the figure at the right. The figure shows the shape of a room. Each unit square represents 1 square foot.**

Question 19.

What is the area of the room in square feet?

Answer:

Figure 1:

l = 4

w = 2

Area = 4 Ă— 2 = 8 sq. ft

Figure 2:

l = 2

w = 4

Area = 2 Ă— 4 = 8 sq. ft

So, the area of the room in square feet is 8 + 8 = 16 sq. ft

Question 20.

What is the perimeter of the room in feet?

Answer:

Figure 1:

l = 4

w = 2

P = 2(l + w)

P = 2(4 + 2)

P = 12 ft

Figure 1:

l = 4

w = 2

P = 2(l + w)

P = 2(4 + 2)

P = 12 ft

So, the perimeter of the room in feet is 12 + 12 = 24 ft

Question 21.

Decompose the figure into two rectangles to find its area. What do you notice?

Answer:

To decompose is to separate into two or more parts. In the above question we have divided the figure into two parts and then find the area of the room.

**Test Practice**

Question 22.

Find the unknown side length of the figure to the right. The perimeter is 26 inches.

(A) 5 inches

(B) 8 inches

(C) 9 inches

(D) 10 inches

Answer: (B) 8 inches

Explanation:

L = 8

W = 5

Opposite sides are equal in the rectangle.

So, option B is the correct answer.

**Reflect**

Use what you learned about perimeter and area to complete the graphic organizer.

Now reflect on the ESSENTIAL QUESTION Write your answer below.

Answer: