A rate is a ratio that compares two related quantities. Common rates are speed = \({distance \over time}\), flow = \({amount \over time}\), and defect = \({errors \over units}\).
How many hours does it take a car to travel 20 miles at an average speed of 20 miles per hour?
| 1 hour | |
| 2 hours | |
| 4 hours | |
| 3 hours |