# Ratios - Concept

###### Explanation

In math, it's sometimes helpful to be able to compare quantities using **ratios**. Ratios are used often in word problems and in Geometry when comparing similar figures. A ratio is a comparison of two quantities. One common ratio example is how many miles in an hour a person drives. Problems that contain ratios involve solving single-step, two-step, or multi-step equations in order to find a quantity or variable.

###### Transcript

Sometimes in Math you're going to see the word ratio, and ratio is just another word for a fraction. To be honest you can use them almost interchangeably it'll make sense in your Algebra one course. If you treat ratios the same way you treat fractions with one tiny exception there's lots of different ways to write a ratio. Lets say we're talking about the fraction one half that's called a fraction it's also called a ratio I could also write it like this 1 with this colon thing two dots and then 2. Those are equivalent ratios, I could also write it using the word 2, 1:2, these are all three different ratios that represent the same idea. In an idea you might express with the ratio often times has to do with how many people or how many of some item there are. For example you could say for every one girl in the class there were two guys yeah, you would say the ratio of girls to guys was 1:2 and for girls that's a good thing right? Cause you have one girl you have 2 guys for every one girl there's two you get to choose from. So that's one place that ratio show up in the real world, you see it really often in schools when they talk about student to faculty ratio. Especially when you're applying to colleges you'll see things like, the student to faculty ratio is 1:9 wait other way around it would be 9:1, 9 students for every one teacher or it might be 12:1. And that affects facts some things like class size, so keep that in mind if you're moving through your Algebra course and also when you look into choosing colleges in your future.