# >> K-12 >> K-12 Basics

How to Find a Ratio Using Fractions

You can use a ratio to compare two numbers or quantities, such as the number of spades to the number of diamonds in a deck of cards. You can write a ratio as two numbers separated by a colon, such as 1:2, or as a fraction with a numerator over a denominator, such as 1/2. This compares the first number to the second number. A ratio written as a fraction has the same properties as a fraction. This means you can reduce it or rewrite it as an equivalent fraction with a different numerator and denominator, which is a ratio in the same proportion.

Instructions

- 1
  Determine two items that you want to compare as a ratio. For example, compare the number of red cars to the number of blue cars in a parking lot.
- 2
  Write the number of the first item you want to compare as a numerator of a fraction over a fraction bar. For example, if there are 5 red cars in a parking lot, write 5 as a numerator over a fraction bar, which results in "5/."
- 3
  Write the number of the second item you want to compare as the denominator of the fraction. For example, if there are 15 blue cars in the parking lot, write 15 as the denominator. This equals 5/15, which is the ratio of red cars to blue cars in the parking lot.
- 4
  Reduce the fraction to simpler terms by dividing the numerator and denominator by the largest number that divides evenly into both. For example, 5 is the largest number that divides evenly into the numerator and denominator, so divide each by 5: 5 divided by 5 equals 1, and 15 divided by 5 equals 3. This results in 1/3 as a ratio in the same proportion as 5/15.

Fruit Ripening Experiments

Advantages & Disadvantages of Weathering