Henrico County Public Schools

# Using a Proportion to Solve Percent Problems

After completing this unit you should be able to:

• solve consumer-application problems involving tips, discounts, sales tax and simple interest (7.4)
• use proportions to solve practical problems which include percents (7.6)
• solve practical problems involving percents and proportions: problems of varying complexities that involve real-life data (8.3)
• solve problems using proportions (8.17).

There are a variety of ways to solve percent problems. (fortunately, the PROPORTION METHOD will work for all three types of questions, as well as percent increase and decrease.

• What number is 75% of 4?
• 3 is what percent of 4?
• 75% of what number is 3?

Use a number line and place the numbers in the correct position. You can then convert this palcement into a proportion.

After the numbers and the unknown (variable) are placed in the proportion formula, you will "cross multiply", meaning to find the products of each pair of numbers that are diagonally across in the proportion. Then you solve for the variable.

Worksheets are available in two formats:

 Basic Types Pop up Window PDF Format Consumer Pop up Window PDF Format Thoughtful Pop up Window PDF Format

LESSONS

Find Percent

Find the Whole

Find the Part

Increase/Decrease