Download Example 2 Identify Proportional Relationships

Lesson 4-2
Example 1 Identify Proportional Relationships
PIZZA Sal’s Pizzeria sells large pizzas for $11 but charges a $2 delivery fee per
order. Is the cost of an order proportional to the number of pizzas ordered?
Find the cost for 1, 2, 3, and 4 pizzas and make a table to display numbers and cost.
1
13
Pizzas Ordered
Cost ($)
2
24
3
35
4
46
For each number of pizzas, write the relationship of the cost and number of pizzas as a
ratio in simplest form.
cost of order

pizzas ordered
13
or 13
1
24
or 12
2
35
or 11.67
3
46
or 11.50
4
Since the ratios of the two quantities are not the same, the cost of an order is not
proportional to the number of pizzas ordered. The relationship is nonproportional.
Example 2 Identify Proportional Relationships
RECIPES A lemonade recipe calls for 1.5 cups of lemon juice, 6 cups of cold water,
and 1 cup of sugar to be mixed together. Is the amount of water used proportional
to the amount of lemon juice used?
Find the amount of water and lemon juice needed for different numbers of pitchers of
lemonade and make a table to show these measures.
Cups of Lemon Juice
Cups of Water
Cups of Sugar
1
2
6
1
1
3
12
2
1
2
18
3
4
6
24
4
For each number of cups of water, write the relationship of the amount of water to the
number of cups of lemon juice.
cups of water

cups of lemon juice
6
or 4
1. 5
12
or 4
3
18
or 4
4 .5
24
or 4
6
Since the ratios between the two quantities are all equal to 4, the amount of water used is
proportional to the amount of lemon juice used.