Proportions Notes

Proportions Notes

by Jennifer Mackie

Make these 2 ratios equivalent

Fill in the Blank

What is the scale for the following ratio?

$$\frac{5}{6}=\frac{15}{18}$$  

​What's missing?

Fill in the Blank

What's the scale?

$$\frac{8}{32}=\frac{12}{48}$$  

​Proportion

​an equation that shows two ratios that are equivalent

​

​It's just like the ratio table but with an equal sign in between.

Fill in the Blank

$$\frac{8}{M}=\frac{12}{48}$$  

What's the value of M?

Fill in the Blank

$$\frac{400}{60}=\frac{1000}{T}$$  

What's the value of T?

​Steps to solving a proportion

​1. Draw arrows showing which direction you will be moving. An arrow needs to be pointing to the variable.

​Arrows should be on BOTH sides of the proportion going in the same direction! (Which way is easiest to go?)

​Step 2

​Find the factor needed to multiply or divide to move in the direction you chose.

​You may need to simplify the ratio to find a good factor to use.

​Are the arrows pointing to the larger number (MULTIPLY) or the smaller number (DIVIDE)?

​Step 3

Mulitiply the other side by the factor found.

Multiple Choice

Determine whether each pair of ratios forms a proportion

• Proportion

• Not a Proportion

Multiple Choice

Determine whether each pair of ratios forms a proportion

• Proportion

• Not a Proportion

Multiple Choice

The ratio of a quarterback's completed passes to attempted passes is 7 to 8. If he attempted 24 passes, how many did he complete?

• 21 passes

• 8 passes

• 3 passes

• 27 passes

Multiple Choice

It takes Emma 18 minutes to type and spell check 14 pages of manuscript. How long will it take her to type and spell check 77 pages?

• 18 minutes

• 99 minutes

• 60 minutes

• 1,386 minutes

Multiple Choice

If a car travels 280 miles in 7 hours, how far will it travel in 12 hours?

• 480 miles

• 1,960 miles

• 84 miles

• 25 miles

Multiple Choice

Ramon travels 20 miles in 20 minutes, how many miles can he travel in 120 minutes?

• 120 miles

• 200 miles

• 10 miles

• 40 miles

Multiple Choice

12 ounce shampoo bottle lasts Mike 16 weeks.  How long would you expect an 18-ounce bottle of the same brand to last him?

• 24 weeks
• 6 weeks
• 30 weeks
• 20 weeks

Multiple Choice

A cake recipe calls for 1.5 cups of milk and 3 cups of flour. Seth made a mistake and used 5 cups of flour. How many cups of milk should he use to keep the proportions correct?

• 2.5 cups milk
• 1.75 cups milk
• 2 cups flour
• 2.25 cups milk