1. Section 11.1 Consumer Mathematics

2. What You Will Learn Percent, Fractions, and Decimal Numbers
Percent Change
Percent Markup and Markdown
Other Percent Problems

3. Percent
The word percent comes from the Latin per centum, meaning “per hundred.”
A percent is a ratio of some number to 100.

4. To Change a Fraction to a Percent
1. Divide the numerator by the denominator to obtain a decimal number.
2. Multiply the decimal number by 100 (which has the effect of moving the decimal point two places to the right).
3. Add a percent sign.

5. Example 1: Converting Fractions to Percents
Change each of the following fractions to a percent.

6. Example 1: Converting Fractions to Percents
Solution

7. Example 1: Converting Fractions to Percents
Solution

8. Example 1: Converting Fractions to Percents
Solution

9. To Change a Decimal Number to a Percent
1. Multiply the decimal number by 100.
2. Add a percent sign.

10. Example 2: Converting Decimal Numbers to Percents
Change each of the following decimal numbers to a percent.
a) b) c)

11. Example 2: Converting Decimal Numbers to Percents
Solution

12. To Change a Percent to a Decimal Number
1. Divide the number by 100.
2. Remove the percent sign.

13. Example 3: Converting a Percent to a Decimal Number
a) Change 35% to a decimal number.
b) Change 69.8% to a decimal number.

14. Example 3: Converting a Percent to a Decimal Number
Solution

15. Percent Change
The percent increase or decrease, or percent change, over a period of time is found by the following formula:

16. Percent Change
If the amount in the latest period is greater than the amount in the previous period, the answer will be positive and indicate a percent increase.
If the amount in the latest period is smaller than the amount in the previous period, the answer will be negative and indicate a percent decrease.

17. Example 6: Most Improved Baseball Team
In 2010, the Major League Baseball team with the most improved record for winning games was the San Diego Padres. In 2009, the Padres won 75 games. In 2010, the Padres won 90 games. Determine the percent increase in the number of games won by the Padres from 2009 to 2010.

18. Example 6: Most Improved Baseball Team
Solution
There was a 20% increase in the number of games won 2009 to 2010.

19. Percent Markup
The following formula represents percent markup or markdown on cost.
A positive answer indicates a markup.
A negative answer indicates a markdown.
Percent markup or markdown on cost

20. Example 8: Determining Percent Markup
Holdren Hardware stores pay $48.76 for glass fireplace screens. They regularly sell them for $ At a sale they sell them for $ Determine
a) the percent markup on the regular price.
b) the percent markup on the sale price.

21. Example 8: Determining Percent Markup
Solution a)
The percent markup on the regular price was about 63.8%.

22. Example 8: Determining Percent Markup
Solution b)
The percent markup on the sale price was about 43.5%.

23. Example 10: Down Payment on a Condominium Home
Melissa Bell wishes to buy a condominium home for $189,000. To obtain the mortgage loan, she must pay 20% of the selling price as a down payment. Determine the amount of Melissa’s down payment.

24. Example 10: Down Payment on a Condominium Home
Solution
x = 20% of the selling price
= 0.20 (189,000)
= $37,800
Melissa’s down payment will be $37,800.