Digits, Grade 7, Volume 1, Homework Helper

6-2: Unit Rates

Key Concept

A rate is a ratio that compares quantities measured in different units. A unit rate is the rate for one unit of a given quantity. When a unit rate is written as a fraction, the denominator is 1 unit. The 1 in a unit rate is read as “per.”

If a car travels 120 mi on 4 gal of gasoline, then the rate is fraction 120 ml , over 4 gal end fraction . .

The unit rate is fraction 30 ml , over 1 gal end fraction . comma or 30 miles per gallon.

Part 1

Example Finding Unit Rates

A lobster molts, or sheds its shell, 20 times over a period of 5 years. How many times per year does the lobster molt?

Solution

The ratio of the number of molts to the number of years is fraction 20 , molts , over 5 , years end fraction . .

Finding an equivalent ratio.

The unit rate is fraction 4 , molts , over 1 , year end fraction . comma or 4 molts per year.

The lobster molts 4 times per year.


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Table of Contents

Digits, Grade 7, Volume 1, Homework Helper Unit A: Number and Operations Unit B: Expressions, Equations, and Relationships Unit C: Measurement and Geometry Unit D: Proportionality English/Spanish Glossary Formulas Math Symbols Formulas Measures Properties