Ratios are considered rates when they compare two different units, like miles per hour or cost per ounce. A unit rate is one in which the numerator of the fraction is compared to a denominator of one unit.

That way you can tell for instance, like how much one ounce of something costs and you’ll see unit rates a lot at the grocery store, under or next to the price of an item. It will tell you how much that item cost for every one ounce or for every one thing in the package.

Next Lesson: Percentages

The transcript is for your convenience

Let’s look at a problem dealing with rates and unit rates. Dave is driving 240 miles to his aunt and uncles house. If he gets there in four hours how many and he here’s the key right here in the question, how many miles per hour did he drive on average? In that question, they’re telling you how to set up the problem. They’re telling you to put miles over hours, so we’re going to start with that, miles per hour. Now we can substitute the information in from the product, so they told us how many miles. He’s going 240 miles and they told us how many hours, four hours, so we can put that into our rate, 240 miles for his four hours.

Right now this would be considered a rate since we have two different units of miles in our hours, but to determine our unit rate or to figure out his average, we would need to divide or simplify our rate to find our unit rate. If we want to have a denominator of one then we’re going to have to divide four by four to get our one and if we divide our denominator by four then we must also divide our numerator by four. 240 divided by four is 60, this is miles per hour, so what this unit rate tells us, is that on average, he was going 60 miles for every one hour, so your answer could be written as, 60 miles per hour, is how fast Dave was going on average.

Next Lesson: Percentages