Skill: Interpret a unit rate

A unit rate tells how much of one quantity corresponds to exactly $1$ unit of another quantity. The words and units tell you what the answer means.

Example: A car travels $(150)$ miles in $3$ hours. What is the car’s speed in miles per hour?

1. Write the rate:

$$\frac{150\text{ miles}}{3\text{ hours}}$$

2. Divide both quantities by $3$ so the number of hours becomes $1$:

$$\frac{150\div 3\text{ miles}}{3\div 3\text{ hours}} = \frac{50\text{ miles}}{1\text{ hour}}$$

3. Interpret the unit rate:

$$50\text{ miles per hour}$$

This means the car travels $(50)$ miles in $1$ hour.

You can also calculate it by dividing:

$$150\div 3=50$$

So, the car’s unit rate is $(50)$ miles per hour. The order matters: miles divided by hours gives miles per hour.