Grade 7 · Unit 1 · Lesson 1 · part 4 of 6
Every ratio gives two unit rates
Every ratio gives you two unit rates, depending on which amount you make into 1.
Every ratio gives two unit rates
Every ratio gives you two unit rates, depending on which amount you make into 1. Julia's walk gives:
Miles per hour: make the hours 1
What do I multiply 14 hour by to get 1? Its reciprocal, 4.
2 miles for each hour. Use it when you know the hours and want the miles.
Hours per mile: make the miles 1
What do I multiply 12 mile by to get 1? Its reciprocal, 2.
12 hour for each mile. Use it when you know the miles and want the hours.
Same question both times: what do I multiply by to get 1? Then the other amount gets the same multiplier. The unit rate you want is the one that answers the question.
| Hours | Miles |
|---|---|
| 1 | 2 |
| 113 | 2 × 43 = 83 = 223 |
| Miles | Hours |
|---|---|
| 1 | 12 |
| 5.2 | 5.2 × 12 = 2.6 |
In 113 hours, Julia walks 223 miles. To walk 5.2 miles, she needs 2.6 hours. Same walk, two unit rates, and each one answers its own kind of question.