Chapter 6: Percents

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42430_Cleaves_ch06 4/12/04 1:22 PM Page 187 5. Shares of McDonald’s, the world’s largest hamburger restaurant chain, rose 51% this year. Find the new share price if the stock sold for $24.25 last year. 100% 51% 151% $36.62 3 Find the rate or the base in increase or decrease problems. Many kinds of increase or decrease problems involve finding either the rate or the base. The rate is the percent of change or the percent of increase or decrease. The base is still the original amount. How To Find the rate or the base in increase or decrease problems 1. Identify or find the amount of increase or decrease. P 2. To find the rate of increase or decrease, use the percentage formula R = . B amount of change R = original amount P 3. To find the base or original amount, use the percentage formula B = . R amount of change B = rate of change EXAMPLE During the month of May, a graphic artist made a profit of $1,525. In June she made a profit of $1,708. What is the percent of increase in profit? What You Know Original amount New amount Solution Plan = = $, 1 525 $, 1 708 Amount of increase = new amount − original amount amount of increase Percent of increase = original amount What You Are Looking For Percent of increase Solution Amount of increase = $, 1 708 − $, 1 525 = $ 183 $ 183 Percent of increase = $, 1 525 = 012 . × 100% = 12% Conclusion The percent of increase in profit is 12%. Subtract. Divide. Convert to % equivalent. In some cases you may not have enough information to determine the amount of increase or decrease. Then we must match the rate with the information we are given. EXAMPLE At Best Buy the price of a DVD player dropped by 20% to $179. What was the original price to the nearest dollar? <strong>Percents</strong> 187
42430_Cleaves_ch06 4/12/04 1:22 PM Page 188 What You Know Reduced price = new amount = $ 179 Rate of decrease = 20% What You Are Looking For Original price Solution Plan Not enough information given to find the amount of decrease. Rate of reduced price = 100% − rate of decrease Solution B= P R reduced price Original price = rate of reduced price Rate of reduced price = 100% − 20% = 80% $ 179 Original price = 80% 179 = 08 . = $ 223. 75 = $ 224 Convert % to decimal equivalent Divide. Round to nearest dollar. Conclusion The original price of the DVD player was $224. Ti p Be Sure to Use the Correct Rate When using the percentage formula, the description for the rate must match the portion. Look at the preceding example and the example on p. 186 DVD Problem Jeans Problem Form of percentage formula B = P R P RB Description of rate Rate of reduced price Rate of new amount Description of portion Reduced price New amount STOP and Check 1. Johanna Helba reported sales of $23,583,000 for the third quarter and $38,792,000 for the fourth quarter. What is the percent of increase in profit? Round to the nearest tenth of a percent. 64.5% 3. Maura Helba showed a house that was advertised as a 10% decrease on the original price. The sale price is $148,500. What was the original price? $165,000 2. Stephen Helba reduced his college spending from $9,524 in the fall semester to $8,756 in the spring semester. What percent was the decrease? Round to the nearest percent. 8% 4. You know that a DVD is reduced 25% and the amount of reduction is $6.25. Find the original price and the discounted price of the movie. Original price: $25 Discounted price: $18.75 5. A used truck is reduced 48% of its new price. You know the used price is $14,799. Find the new price to the nearest dollar. $28,460 188 <strong>Chapter</strong> 6
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Chapter 6: Percents

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