A ratio is a quantity that expresses the proportional amount of one quantity in relation to another. For example, if there are 2 boys and 3 girls in a class, we would write the ratio of boys to girls as 2:3. Sometimes, we will need to write ratios as a decimal. The steps below will show you how to convert ratios into decimals.
Write the ratio as a fraction. As stated earlier, ratios are typically written with a colon. In our example, the ratio of boys to girls is 2:3. The ratio can be converted to a fraction by replacing the colon with a fraction bar. For example, 2:3 can be written as 2/3.
Divide the numerator (top number) by the denominator (bottom number) in your fraction. In our example, if you divide 2/3, you get .666666. . .
If necessary, round the decimal. If your decimal goes on for several places, as our example does, you will need to round it. Sometimes, you may be asked to round to a certain number of places. If not, round to two decimal places. so, we would round our number to .67.
Express your answer as a ratio. So, the ratio of boys to girls in the class is .67.