A unit rate is simply a ratio where the second number in the comparison is one. 65 miles per hour, is a unit rate because it is 65 miles per one hour. $2.50 per pound, is a unit rate because you would pay $2.50 for every pound that you purchased. Finding an equivalent ratio, which was covered in the previous lesson, is how you would find the unit rate. To get the second number down to one, you would have to divide it by itself. Remember, whatever you do to one number, you would have to do to both. So let’s say a family goes on a road trip.
The dad keeps a measure of his gas mileage. He knows that he got 120 miles for 10 gallons of gas. To convert this into a unit rate, we have to make the second number a 1. To do that, we have to divide 10 by 10. If we divide the 10 by 10, we also have to divide the 120 by 10, so we would know that he got 12 miles per gallon. Here’s another example outside of a story problem:
We can see from the above math that if a student reads 45 pages in 30 minutes, she is reading at a speed of 1.5 pages per minute.