How to Set Up Proportions

Set up the following proportion: Pens are 3 for $0.69 at the supply store. What proportion can be used to find c, the amount it will cost Mrs. Faber to buy 180 pens?

Set up the following proportion: It cost Jericho and his 3 friends $20 to get into the skating rink. What proportion can be used to find c, the amount it will cost Jericho’s parents if they have Jericho’s birthday party at the skating rink and pay for Jericho and all 24 of his classmates?

Set up this proportion: Vito uses 9 liters of water to water 24 flower pots. He is wondering how many liters of water (w), it would take to water 40 flower pots. He assumes he'll use the same amount of water on each pot.

Set up the following proportion: Alice earned $20.40 in 3 hours. At the same rate, what would Alice make in 8 hours?

A recipe for fruit salad includes 1/3 cup of grapes for 4 servings. How many cups of grapes are needed for 30 servings of this fruit salad?

Set up the proportion box based on the given labels.

d

e

f

g

26

4

100

30

34

x

1/3

Set up this proportion: Vito uses 9 liters of water to water 24 flower pots. He is wondering how many liters of water (w), it would take to water 40 flower pots. He assumes he'll use the same amount of water on each pot.

An engineer created a scale drawing of a building using a scale in which 0.25 inch represents 2 feet. The length of the actual building is 250 feet. What is the length in inches of the building in the scale drawing? Set up the proportion box based on the given labels.

e

f

g

d

25

0.25

2

1.75

x

100

20

250

How would you set up a proportion?

An engineer created a scale drawing of a building using a scale in which 0.25 inch represents 2 feet. The length of the actual building is 250 feet.

 

What is the length in inches of the building in the scale drawing?

Set up the proportion box based on the given labels.

e

f

g

d

1.75

20

x

25

100

250

2

0.25

We can tell if ratios are proportional by...

• top times top, bottom times bottom

• flipping the second and multiplying

• Cross Multiplying (Butterfly!!!)