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McGraw-Hill Math Grade 3 Chapter 12 Test Answer Key
Count or multiply to find the area of each figure.
Question 1.
Answer:
6 square units
Explanation:
I counted by 1’s
There are 6 squares in the above figure
So, the area of the given figure is 6 square units.
Question 2.
Answer:
4 square units
Explanation:
There are 3 squares and 2 triangles which is 1 square
So, the area of the figure is 4 square units.
Question 3.
Answer:
6 square units
Explanation:
I counted by 1’s
There are 6 squares in the above shape
So, the area of the given figure is 6 square units.
Question 4.
Answer:
12 square units
Explanation:
The multiplication sentence that tells the area of the above figure is 2 x 6 = 12
So, the area of the given figure is 12 square units.
Question 5.
Answer:
11 square units
Explanation:
I counted by 1’s
There are 11 squares in the above shape
So, the area of the given figure is 11 square units.
Question 6.
Answer:
22 square units
Explanation:
I counted by 1’s
There are 22 squares in the above shape
So, the area of the given figure is 22 square units.
Write a multiplication sentence for each area model.
Question 7.
Answer:
1 x 3 = 3
Explanation:
There is 1 row and 3 columns of squares
The multiplication sentence for the given area model is 1 x 3 = 3.
Question 8.
Answer:
5 x 5 = 25
Explanation:
There is 5 rows and 5 columns of squares
The multiplication sentence for the given area model is 5 x 5 = 25.
Question 9.
Answer:
2 x 7 = 14
Explanation:
There is 2 rows and 7 columns of squares
The multiplication sentence for the given area model is 2 x 7 = 14.
Look at the area model. Circle the multiplication sentence that matches.
Question 10.
4 × (4 + 2) = 16 square units
2 × (4 + 2) = 16 square units
4 × (2 + 2) = 16 square units
Answer:
Explanation:
There are 4 rows of squares
In that 2 columns are brown and 2 columns are yellow
So, the the multiplication sentence that matches with the area model is 4 x (2 + 2) = 16 square units.
Question 11.
Selma is decorating the cover of her journal with stickers. The cover is 6 units by 7 units. Each sticker covers 1 square unit. How many stickers does Selma need to decorate every unit of the whole journal cover? Find 6 × 7 by breaking apart 7. Use 3 for one of the addends. Use the area model to help you.
Answer:
Selma need 42 stickers to decorate every unit of the whole journal cover
Explanation:
Selma is decorating the cover of her journal with stickers
The cover is 6 units by 7 units
We need to find area of the journal cover
6 x 7
Breaking apart 7 as 3 ad 4
Area = 6 x ( 3 + 4 )
= (6 x 3) + (6 x 4)
= 18 + 24
= 42
So, area of the cover is 42 square units
Each sticker covers 1 square unit
So, Selma need 42 stickers to decorate every unit of the whole journal cover.
What fraction of the total area ¡s red? Write the fraction.
Question 12.
Answer:
\(\frac{1}{4}\)
Explanation:
There are 4 equal parts in the whole
1 part of the whole is shaded
So, the fraction that represents the shaded part is \(\frac{1}{4}\).
Question 13.
Answer:
\(\frac{1}{8}\)
Explanation:
There are 8 equal parts in the whole
1 part of the whole is shaded
So, the fraction that represents the shaded part is \(\frac{1}{8}\)
Question 14.
Answer:
\(\frac{1}{6}\)
Explanation:
There are 6 equal parts in the whole
1 part of the whole is shaded
So, the fraction that represents the shaded part is \(\frac{1}{6}\)
Find the perimeter.
Question 15.
Answer:
27 m
Explanation:
Perimeter of the triangle is sum of all the sides
That is 9 + 9 + 9
So, perimeter is 27 m.
Question 16.
Answer:
8 cm
Explanation:
Perimeter of the square is sum of all the sides
That is 2 + 2 + 2 + 2
So, perimeter is 8 cm.
Question 17.
Answer:
26 ft
Explanation:
Perimeter of the rectangle is sum of all the sides
Opposite sides of the rectangle are equal in lengths
That is 9 + 9 + 4 + 4
So, perimeter is 26 ft.
Find the length of the unknown side.
Question 18.
perimeter: 19 m
unknown side: _____________
Answer:
Unknown side = 5 m
Explanation:
Given perimeter = 19 m
Perimeter of a shape is sum of all the sides
4 + 3 + 4 + 3 + ? = 19
14 + ? = 19
19 – 14 = 5
So, unknown side = 5 m.
Question 19.
perimeter: 15 in
unknown side: ______________
Answer:
Unknown side = 6 in
Explanation:
Given Perimeter = 15 in
Perimeter of the triangle is sum of all the sides
That is 3 + 6 + ? = 15
9 + ? = 15
15 – 9 = 6
So, unknown side = 6 in.
Question 20.
perimeter: 13 ft
unknown side: _______________
Answer:
Unknown side = 3 ft
Explanation:
Given perimeter = 13 ft
Perimeter of a shape is sum of all the sides
2 + 2 + 2 + 4 + ? = 13
10 + ? = 13
13 – 10 = 3
So, unknown side = 3 ft.
Use the picture to help you solve.
Question 21.
An artist charges $8 for each square unit of surface space that she paints. How much did she charge for this painting?
Answer:
$80
Explanation:
An artist charges $8 for each square unit of surface space that she paints
The area of the painting is 2 x 5 = 10 square unit
So, multiply 10 with $8 to find the amount the artist charged for the painting
10 x $8 = $80
So, the artist charged $80 for this painting.