Lesson 5: Compare Ratios6.AT.3

I can…

I can compare ratios by finding unit rates or using equivalent ratios.

Key words

• Unit rate — A rate for just 1 of something, like cost for 1 item.
• Equivalent ratio — Two ratios that mean the same thing.
• Compare — To look at ratios and see which is bigger, smaller, or equal.
• Simplify — To make a ratio as small as possible while keeping the same comparison.
• Common denominator — A bottom number that two fractions can share so you can compare them.

Steps

1. Chef Reyes uses 3 tbsp cocoa for 5 oz milk (3:5). Chef Tran uses 4 tbsp for 7 oz milk (4:7).
2. I cannot compare yet because the milk amounts are different.
3. I scale both to 35 oz of milk. For Reyes: 5 x 7 = 35, so 3 x 7 = 21 tbsp, giving 21:35.
4. For Tran: 7 x 5 = 35, so 4 x 5 = 20 tbsp, giving 20:35.
5. Now the milk is equal, so I compare cocoa: 21 > 20, so Chef Reyes's cocoa is more chocolatey.

Try it

A bakery sells 4 muffins for $10 and another bakery sells 6 muffins for $14. Which bakery has the lower price per muffin?

Check your answer

The second bakery

First bakery: $10÷4 = $2.50 per muffin. Second bakery: $14÷6 ≈ $2.33 per muffin. The second bakery has the lower price.

Sentence starter

I know ___ because ___.

Goal: I can explain my comparison using the words unit rate, equivalent ratio, compare, and common denominator.