Solve Percent Problems

Remember:

Videos

Fractions are a part to whole relationship.

A percent is out of 100.

Practice Sites

Math Goodies - Scroll to the bottom of the instructions and there are 5 problems you can practice. Enter your answer in the answer box and then click the enter button to see if you are right.

Math Playground Percent Shopping - Use your skill to calculate sale prices.

Since percent, ratio and fractions can be compared once they are in the same form, we can use this fact to help us solve percent problems using a percent proportion. A proportion is an equation that show two ratios are equal. Let's think one through.

Problem. 10 is 25% of what number?

This is what I know from this question. I know the 10 is a part. I do not know what the whole is so I will use a variable, usually X to represent what I do not know. Since part to whole relationships can be set up as fractions I will use these to solve the problem. My fraction will look like this.

I know that 25% is 25 out of 100 as it is a percent and a percent is out of 100. So my fraction will look like this.

Now that I know these things I can solve the problem by setting up a percent proportion. Since the two ratios are equal, I will put an equals sign between them. My problem will look like this.

I will use cross products to solve this problem. That means multiplying a numerator and the opposite denominator. here are the steps.