Concept
A rate is a ratio that is used to compare different kinds of quantities.
A unit rate describes how many units of the first type of quantity corresponds to one unit of the second type of quantity.
Rule
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Write the ratio of the two quantities as a fraction.
Quantity 1 per Quantity 2 means Quantity 1Quantity 2
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Calculate unit rate by dividing the numerator by the denominator.
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Use the unit rate to write and solve the proportion.
Example
The table shows how many miles a truck driver travels over a time. How many miles will he have driven after 8 hours?
Time Hours |
Distance miles |
2 |
120 |
3 |
180 |
4 |
240 |
5 |
30 |
Solution
Write the ratio of any data point as a fraction.
DistanceHours = 120 miles2 hours
Calculate unit rate by dividing the numerator by the denominator.
DistanceHours = 60 miles per hour
Use the unit rate to write and solve a proportion
60 miles1 hour = x miles8 hours
60 × 81 × 8 = 4808
Answer: 480 miles
Pre-requisite Skills
Equivalent Fractions (5.10.5)
Ratios and Fractions (6.6.2)
Multiply Fractions (6.7.7)
Error