When was the last time you used Algebra outside of a classroom? Well, if you drive a car, buy things, cook food, or count on your heart to beat, then you're using ratios, a great tool to find the unknown in situations. A **ratio **is a comparison of 2 or more quantities.

Examples of Ratios:

- Miles per gallon
- Dollars per pound
- Cups of water per cups of rice
- Heart beats per minute

This article focuses on the basics of ratios - how to write them and how to use them to make predictions.

### 1. Learn to Write a Ratio

Dr. Pasture, a rural veterinarian, treats only 2 types of animals — cows and horses. Last week, she treated 12 cows and 16 horses.

1) What is the ratio of cows to horses that she treated?

2) What is the ratio of cows that she treated to the total number of animals that she treated?

Read more to learn how to write these ratios.

### 2. Ratios and Change

On Atlantis, the ancient island of Plato's imagination, athletes compete in either surfing or kayaking.

Surfers: 96

Kayakers: 144

What happens to the ratios when the numbers change? Continue to pretend and imagine that some surfers take up kayaking. Practice writing ratios in the midst of change.

### 3. Using a Ratio to Find the Unknown

How do you use ratios in Algebra? A ratio, which is a comparison of 2 quantities, assists with making wise decisions.

### 4. Ratios & Test Preparation

Unfortunately, you can’t hide from ratios on the PSAT, SAT, ACT, GRE, or GMAT. This article focuses on a skill that is tested on these entrance exams: how to use ratios to make predictions.

### 5. More Ratios & Test Prep

Have you ever seen a question like this?

Students at Dale Senior High School vote to visit the zoo or the aquarium. The ratio of zoo-goers to aquarium-goers is 3:10. If 50 of the students want to visit the aquarium, then how many students in all voted?

Yes, there is enough information to answer the question. Read more to learn how to answer this question.