Name: Date: Lesson 4.3 Real-World Problems: Ratios
Solve.
Example
The ratio of Harry’s money to Lincoln’s money is 6 : 5.
a)
If Harry and Lincoln have a total of $715, how much money does Harry have?
?
Harry
$715
Lincoln
Total amount of money 5
6
1
5
11
units
11
6
unit → $
390
715
6
units →
Harry has $
b)
715
units → $
1
5
4
11
3$
65
5$
5$
65
390
.
If Lincoln has $575, how much money does Harry have?
© Marshall Cavendish International (Singapore) Private Limited.
?
Harry
Lincoln
$575
5
units → $
575
1
unit → $
575
6
6
units →
Harry has $
690
4
5
5$
115
3$
115
5$
690
.
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Name: Date: 1. A box contains red ink pens and blue ink pens. The ratio of the number of red
ink pens to the number of blue ink pens is 6 : 1.
a)
If the total number of ink pens is 1,932, find the number of each type
of ink pens.
Red
1,932
Blue
Total number of ink pens 5
1
units
5
units →
unit →
4
5
units →
3
5
The box contains
b)
red ink pens and
blue ink pens.
If the number of red ink pens is 858, find the number of blue ink pens.
858
Red
?
units →
unit →
The box contains
106
4
5
blue ink pens.
© Marshall Cavendish International (Singapore) Private Limited.
Blue
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Name: Date: 2. A wooden plank is cut into two pieces. The ratio of the length of the two pieces
of wood is 7 : 10.
If the length of the original wooden plank is 952 centimeters, what is the
length of the shorter piece of wood?
b)
If the length of the shorter piece of wood is 168 centimeters, what is the
length of the longer piece of wood?
© Marshall Cavendish International (Singapore) Private Limited.
a)
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Name: Date: Solve.
Example
The ratio of the number of orange trees to the number of apple trees to the
number of pear trees in an orchard is 5 : 6 : 4.
a)
If there are 1,275 trees in the orchard, how many of each type of fruit trees
are there?
Orange
1,275 trees
Apple
Pear
Total number of units 5
5
5
15
6
1
15
units →
1,275
1
unit →
1,275
4
15
5
85
5
units →
5
3
85
5
425
85
5
510
85
5
340
6
There are
4
There are
425
units →
510
units →
340
4
orange trees.
6
3
apple trees.
4
3
pear trees.
© Marshall Cavendish International (Singapore) Private Limited.
There are
108
1
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Name: b)
Date: If there are 720 pear trees, how many trees are there in all?
Orange
?
Apple
Pear
720 trees
4
units →
720
1
unit →
720
4
4
5
180
15
units →
15
3
180
5
2,700
There are
2,700
trees in all.
3. Shelby, Brandon, and Ling shared the cost of lunch in the ratio 2 : 5 : 3.
a)
If lunch cost $250, how much did each person pay?
Shelby
Total number of units 5
1
1
$250
Brandon
5
Ling
© Marshall Cavendish International (Singapore) Private Limited.
units →
unit →
4
5
units →
3
5
3
5
3
5
Shelby paid
.
units →
Brandon paid
.
units →
Ling paid
.
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Name: b)
Date: If Ling paid $24, how much did the lunch cost?
Shelby
?
Brandon
Ling
$24
units →
unit →
4
5
units →
3
5
The lunch cost
110
The number of stickers collected by Maurice, Elle, and Justin is in the ratio 8 : 5 : 7.
a)
If Maurice collected 960 stickers, how many stickers did Elle and Justin
each collect?
b)
If the three children have 1,500 stickers altogether, how many stickers did
they each collect?
© Marshall Cavendish International (Singapore) Private Limited.
4.
.
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Name: Date: Solve.
Example
In a school, the ratio of the number of girls to the number of boys is 7 : 5. In the
same school, the ratio of the number of boys to the number of teachers is 15 : 1.
There are 210 girls in the school. How many boys and teachers are there?
210
Girls
Girls
Boys
Boys
Teachers
Boys : Teachers 5
Girls : Boys 5 7 : 5
3
3
5
:
21
© Marshall Cavendish International (Singapore) Private Limited.
15
:
:
21
units →
210
1
unit →
210
4
21
5
10
15
units →
15
3
10
5
150
150
1
15
So, Girls : Boys : Teachers 5
There are
:
3
3
21
15
boys and
10
1
teachers.
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Name: Date: 5. The ratio of the number of hair clips to the number of ribbons is 5 : 2. The ratio
of the number of ribbons to the number of headbands is 4 : 5. If there are 40 hair
clips, how many ribbons and headbands are there?
40
Hair clips
Hair Clips
Ribbons
Ribbons
Headbands
Hair clips : Ribbons
Ribbons : Headbands 5
55:2
:
3
3
5
:
So, Hair clips : Ribbons : Headbands 5
:
:
unit →
4
5
units →
3
5
units →
3
5
There are
112
ribbons and
headbands.
© Marshall Cavendish International (Singapore) Private Limited.
units →
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Name: Date: © Marshall Cavendish International (Singapore) Private Limited.
6. The ratio of the number of red marbles to the number of green marbles in a bag
is 2 : 3. The ratio of the number of green marbles to the number of blue marbles
is 9 : 4. There are 76 marbles in the bag.
a)
Find the number of red marbles in the bag.
b)
Find the number of green marbles in the bag.
c)
Find the number of blue marbles in the bag.
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Name: Date: Solve.
Example
In the morning, the ratio of the number of seabirds to the number of sea turtles
in a rescue center is 3 : 2. After 15 sea turtles are rescued in the afternoon, the
ratio becomes 9 : 11.
Before
The ratio of the number of seabirds to the number
3
of sea turtles is
2
:
Seabirds
.
Sea turtles
After
The ratio of the number of seabirds to the number of sea turtles becomes
9
:
11
.
The number of seabirds does not change.
seabirds
So, the length of the model for
seabirds
The model for
does not change.
is divided into
9
units.
The model for sea turtles is divided into units of the same size and additional
The additional units represent the
15
11
units.
sea turtles rescued in the afternoon.
Seabirds
Sea turtles
15
a)
How many seabirds are in the rescue center?
5
units →
15
1
unit →
15
4
5
5
3
9
units →
9
3
3
5
27
There are
114
27
© Marshall Cavendish International (Singapore) Private Limited.
units are added to make the total length
seabirds in the rescue center.
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Name: b)
Date: How many sea turtles are in the rescue center in the afternoon?
11
There are
11
units →
33
3
3
5
33
sea turtles in the rescue center in the afternoon.
7. The ratio of the number of newspapers Joshua sold to the number of
newspapers Ron sold was 5 : 3. After Ron sold 28 more newspapers in the
evening, the ratio became 10 : 13.
Before
The ratio of the number of newspapers Joshua sold to the number of
newspapers Ron sold was
:
.
Joshua
Ron
After
The ratio of the number of newspapers Joshua sold to the number of
newspapers Ron sold became
:
.
The length of the model for
does not change.
© Marshall Cavendish International (Singapore) Private Limited.
The model for
is divided into
units.
The model for Ron is divided into units of the same size and additional
units are added to make the total length
The additional units represent the
evening.
units.
newspapers Ron sold in the
Joshua
Ron
28
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Name: a)
Date: How many newspapers did Joshua sell?
units →
unit →
4
5
units →
3
5
Joshua sold
b)
newspapers.
How many newspapers did Ron sell in all?
units →
Ron sold
3
5
newspapers in all.
116
a)
How many members of the club are girls?
b)
How many boys are members of the club in the end?
© Marshall Cavendish International (Singapore) Private Limited.
8. The ratio of the number of boys to the number of girls in a dance club is 5 : 6.
After 6 more boys join the club, the ratio became 13 : 12.
Chapter 4 Lesson 4.3
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