A rate is a ratio that compares two related quantities. Common rates are speed = \({distance \over time}\), flow = \({amount \over time}\), and defect = \({errors \over units}\).
If a car travels 630 miles in 9 hours, what is the average speed?
| 20 mph | |
| 30 mph | |
| 70 mph | |
| 40 mph |