Rate

A rate is a special kind of ratio, of two measurements with different units. It is a comparison of two measurements with different units, such as miles to gallons or cents to pounds. For example, suppose you spend $9.75 on 2.5 pounds of candy. The rate $9.75 / 2.5 pounds compares the money spent to the number of pounds of candy.

When a rate is simplified so it has a denominator of 1, it is called a unit rate. This type of rate is frequently used when referring to statistics.

Example

The civics membership in the U.S. House of Representatives is based on a population in the preceding census. In 1990, the population of the United States was about 248,000,000. There are 435 members in the house. On average, how many people are represented by each member of the house?

Write the rate that compares the population to the number of members of the house. Then devide both the numerator and the denominator by 435.

(248,000,000 people)/(435 members) ~ (570,000 people)/(1 member)

This saying, that the House of Representatives represents about 570,000 people.