Let's begin by reviewing the definitions of ratio and rate. A ratio is the comparison of two numbers by division. There are a few ways to express the ratio of x and y.
x to y, x:y, x/y
A rate, on the other hand, is a specific type of ratio. It is the ratio of measurements having different units of measure. In the table below are a few examples of each.
Ratio
Rate
There are 5 boys and 7 girls in a class. The ratio of boys to girls is 57.
A car burns 20 liters of gas for every 200 km traveled. Gas is burned at a rate of 2 liters200hours.
There are 3 teachers for every 12 children at a school. The ratio of teachers to children is 312.
A runner runs 2 km in 20 minutes. The rate at which the runner runs is 2km20minutes.
There are 100 cars for every 150 people in a city. The ratio of cars to people is 100150.
A woman works 60 hours every 3 weeks. The rate at which she works is 60hours3weeks.
As we can see, both ratios and rates compare two numbers using division. However, rates compare two measurements that involve different units of measure.
