Content

• Steps
• Method 1 of 2: Recording Ratios
• Method 2 of 2: More information on ratios
• Tips

A ratio (in mathematics) is a relationship between two or more quantities of the same kind. Ratios compare absolute values ​​or parts of a whole.For example, the ratio can be used to express the number of apples to the number of oranges in a fruit basket. Knowing how to write ratios will help you with everyday tasks, such as changing the ingredients in a recipe when the servings are doubled, or calculating the number of snacks when the number of guests changes.

Steps

Method 1 of 2: Recording Ratios

1. 1 Designation of ratios. When writing ratios, the following symbols are used: forward slash (/), colon (:), or the preposition "to". For example, if you want to write the ratio for the expression "there are three women for every five men at a party," then do it like this:
   • 5 men / 3 women
   • 5 men: 3 women
   • 5 men to 3 women
2. 2 Record the value of the first given quantity to the left of the ratio symbol. Do not forget about the quantities you are working with (men or women, chickens or goats, meters or centimeters).
   • Example: 20 g flour.
3. 3 Record the value of the second given quantity to the right of the ratio symbol. Don't forget about the quantities you are working with.
   • Example: 20 g flour / 8 g sugar.
4. 4 Simplify the ratio (optional). To do this, divide both terms (numbers) of the ratio by the greatest common divisor (GCD), that is, the largest number by which both terms of the ratio are divided. (The process of simplifying a ratio is the same as simplifying a fraction.)
   • In our example, find the GCD of the numbers 20 and 8. To do this, write down all the divisors of these numbers (divisors are numbers that divide the given number without a remainder). Then find the greatest divisor that appears in the divisor list of both 20 and 8. Here's how to do it:
     • 20: 1, 2, 4, 5, 10, 20
     • 8: 1, 2, 4, 8
   • In our example, GCD = 4. To simplify the ratio, divide 20 and 8 by 4:
   • 20/4 = 5
   • 8/4 = 2
     • Simplified ratio: 5 g flour / 2 g sugar.
5. 5 Convert the ratio to percentages (optional). To do this, follow these steps:
   • Divide the first number by the second. Example: 5/2 = 2.5.
   • Multiply your result by 100. Example: 2.5 * 100 = 250.
   • Write the percent sign: 250%.
   • This means that there are 2.5 units of flour for 1 unit of sugar; similarly, for cooking, you need to take 250% sugar (compared to flour).

Method 2 of 2: More information on ratios

1. 1 The order of the members in the ratio does not matter. The expression "5 apples to 3 pears" is similar to the expression "3 pears to 5 apples". So 5 apples / 3 pears = 3 pears / 5 apples.
2. 2 The ratio can be used to describe the likelihood. For example, the probability of rolling the number 2 on one die is 1/6, or one in six. Note: If you are using a ratio to describe a probability, then the order of the terms matters.
3. 3 You can increase or decrease the ratio. When you simplify the ratio, you decrease it, but you can also increase the ratio. For example, you know that to make 100 g of pasta, you need 2 glasses of water (ratio: 2 glasses of water / 100 g of pasta). If you want to know how many glasses of water it takes to make 200 g of pasta, divide 200 by 100 to get 2. Then multiply this value by 2 glasses (2 * 2 = 4). Thus, the increased ratio will be written as follows: 4 glasses of water / 200 g of pasta (that is, to prepare 200 g of pasta, 4 glasses of water are required).

Tips

• The ratio can be used to describe the likelihood. For example, the probability of rolling the number 2 on one die is 1/6, or one in six.