Lesson 4: Equivalent Ratios6.AT.3

I can…

I can find and check equivalent ratios using multiplication and division.

Key words

• Ratio — A way to compare two amounts, like 3 to 2.
• Equivalent ratios — Two ratios that mean the same thing.
• Rate — A ratio comparing two amounts with different units, like miles per hour.
• Proportion — A math sentence saying two ratios are equal.
• Simplify — To make a ratio smaller while keeping the same comparison.

Steps

1. Chef Montoya's soup serves 8 people, but she needs to serve 32.
2. I find the scale factor: 32 divided by 8 = 4.
3. The recipe uses 3 cups of tomatoes to 2 cups of broth, a 3:2 ratio.
4. I multiply both by 4: 3 x 4 = 12 cups of tomatoes, and 2 x 4 = 8 cups of broth.
5. So 3:2 and 12:8 are equivalent ratios, and the flavor stays the same.

Try it

A store sells 5 notebooks for $8. At this rate, how much would 15 notebooks cost?

Check your answer

$24

15 is 3 times 5, so the cost is 3 × $8 = $24. The ratio 5:8 scales to 15:24.

Sentence starter

I know ___ because ___.

Goal: I can explain my reasoning using the words equivalent ratios, rate, proportion, and simplify.