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 180 miles in 9 hours, what is the average speed?
| 55 mph | |
| 30 mph | |
| 50 mph | |
| 20 mph |