Section 11.1 Consumer Mathematics

# Section 11.1 Consumer Mathematics

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## Section 11.1 Consumer Mathematics

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1. Section 11.1Consumer 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. To Change a Decimal Number to a Percent • 1. Multiply the decimal number by 100. • 2. Add a percent sign.

7. Example 2: Converting Decimal Numbers to Percents • Change each of the following decimal numbers to a percent. • a) 0.14 b) 0.893 c) 0.7625

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

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

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

11. 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.

12. 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.

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

14. 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

15. Example 8: Determining Percent Markup Holdren Hardware stores pay \$48.76 for glass fireplace screens. They regularly sell them for \$79.88. At a sale they sell them for \$69.99. Determine a) the percent markup on the regular price. b) the percent markup on the sale price.

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

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

18. 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.

19. 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.