Math in Focus Grade 4 Chapter 12 Practice 1 Answer Key Area of a Rectangle

This handy Math in Focus Grade 4 Workbook Answer Key Chapter 12 Practice 1 Area of a Rectangle detailed solutions for the textbook questions.

Math in Focus Grade 4 Chapter 12 Practice 1 Answer Key Area of a Rectangle

Find the area of each figure.

Example

There are 3 rows of one-inch squares.
Each row has 4 one-inch squares.
3 × 4 = 12
There are 12 one-inch squares covering rectangle A.
Area of rectangle A = 12 in.²

Question 1.

There ore ___________ rows of one-meter squares.
Each row has __________ one-meter squares.
________ × ________ = ________
There are __________ one-meter squares covering rectangle B.
Area of rectangle B = ___________ m²
Answer:
There are 7 rows of one-meter squares.
Each row has 3 one-meter squares.
7 × 3 = 21
There are 21 one-meter squares covering rectangle B.
Area of rectangle B = 21 m²

Look at the rectangles in the grid. Write the length, width, and area of each rectangle in the grid. Give your answers in the correct units.

Question 2.


Answer:

Complete to find the area of each figure.

Question 3.

Area = length × width
= __________ × __________
= ___________ yd²
The area is ___________ square yards.
Answer:
Length = 5 yards
width = 2 yards
Area = length × width
=5yd × 2yd
= 10 yd²
The area is 10 square yards.

Question 4.

Area = __________ × __________
= ___________ ft²
The area is ___________ square feet.
Answer:
In the above image we can observe length and width.
Length = 16 feet
width = 4 feet
Area = 16 feet × 4 feet
= 64 ft²
The area is 64 square feet.

Find the perimeter and area of each rectangle or square.

Example

Perimeter = 18 ft
Area = 14 ft²

Question 5.

Perimeter = ___________ in.
Area = __________ in²
Answer:
In the above image we can observe a square.
Side = 4 inch
Perimeter of square = 4 × S
= 4 × 4 inch
= 16 inch
Perimeter of square = 16 inch
Area of a square = side²
= 4 × 4
= 16 in²
Area of square = 16 in²
Question 6.

Perimeter = ___________ ft.
Area = __________ ft²
Answer:
In the above image we can observe a rectangle.
length = 6 feet
width = 2 feet
Perimeter of rectangle = 2 (l + w)
= 2 (6 feet + 2 feet)
= 2 (8 feet)
= 16 feet
Perimeter of rectangle = 16 feet.
Area of rectangle = length x width
= 6 feet × 2 feet
= 12 ft²
Area of rectangle = 12 ft²
Question 7.

Perimeter = ___________ yd.
Area = __________ yd²
Answer:
In the above image we can observe a rectangle.
length = 5 yards
width = 4 yards
Perimeter of rectangle = 2 (l + w)
= 2 (5 yards + 4 yards)
= 2 (9 yards)
= 18 yards
Perimeter of rectangle = 18 yards.
Area of rectangle = length x width
= 5 yards × 4 yards
= 20 yd²
Area of rectangle = 20 yd²

Solve. Show your work.

Example

Ashley has a rug that measures 3 yards by 2 yards on her bedroom floor.
What area of her bedroom floor is covered by the rug?

Area = length × width
= 3 × 2
s = 6 yd²
The area of her bedroom floor covered by the rug is 6 square yards.

Question 8.
Paula wants to paint one of the walls in her room blue. The wall measures 5 meters by 3 meters. What is the area of the wall she has to paint?

Answer:
In the above image we can observe length and width.
Length = 5 m
width = 3 m
Area of the wall = length ×  width
= 5 m x 3 m
= 15 m²
The area of the wall she has to paint is 15 square meters.
Question 9.
The area of a nature reserve is 100 square miles. Oak trees were planted on a square plot of land in the nature reserve with sides that measure 8 miles each. What area of the nature reserve is not covered by oak trees?
Answer:
The area of a nature reserve = 100 square miles.
The area of oak trees = 8 mi x 8 mi = 64 mi²
The area not covered by oak trees = area of a nature reserve – area of oak trees
= 100 – 64
= 36 mi²
Area of the nature reserve is not covered by oak trees are 36 square miles.

Solve. Show your work.

Question 10.
Yolanda has a piece of rectangular fabric measuring 30 centimeters by 9 centimeters. She uses half of the material to make a puppet. What is the area of the leftover fabric?
Answer:
Area of the rectangular fabric = length ×  width
= 30 cm ×  9 cm
= 270 cm²
She used half of the material to make a puppet.
= 270/2
= 135 cm²
The area of the leftover fabric is 135 square centimeters.

Estimate the area of each figure in square units.

Example

Estimated area = 14 – 15 square units

Question 11.

Estimated area = __________ square units.
Answer:
Estimated area = 13 – 14 square units.

Question 12.

Estimated area = __________ square units.
Answer:
Estimated area = 6 – 7 square units.