7.2 Solving Percent Problems Key words is solving % problems What number is a % of a value?

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Gilbert Wilkerson
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1 7.2 Solving Percent Problems Key words is solving % problems What number is a % of a value? What number n or some variable is of - #17. What number is 6% of 250? n n #18. What number is 82% of 00? n n 26 - What percent x or some variable(p) # is what percent of 20? 16 x x x 0. 8 x or x 80% Always have to change answer % #20. 1 is what percent of 25? 1 x x 1 25 x x or x 52% # is 12% of what number? n n n 65 # is % of what number? n n n 90 #2. What number is 0. 8% of 12? n n #2. What number is 5. 6% of 00? n n

2 # is what percent of 0, 000? 0.5 x 0, ,000 x x x % # is what percent of 15? 0. x x x x 2% #27.. is 7. 5% of what number? n n # is 20% of what number? n n Find is replaced by What number is or n #29. Find 7 1 % of 600? What number is 7 1 % of 600? n 7.25% 600 n #0. Find 1 % of 800. What number is 1 % of 800. n 1.75% 800 n # 66 2 % of what number is 28? 66 2 % n % in fraction form 2 2 n 28 n Do NOW a. What number is 20% of 80? b. 9 is what percent of 16? c. 150 is 66 2 % of what number? Note: 66 2 % is the fraction 2 d. Find 160% of Find What number is ans. a. 192 b % c. 5 d

3 Alternate approach:% formula Amount percentbase base value following of Example5 What number is 160% of 15. 8? Amount percentbase A 160% 15.8 A Example6 1 is what percent of 2? Amount percentbase 1 p 2 2 p 1 p change to %, 75% Example is 1 percent of what number? Amount percentbase % b 1 % in fraction form b b Do NOW using A % b a. What number is 20% of 60? b. 15 is what percent of 2? c is 66 2 % of what number? Note: 66 2 % is the fraction 2 d. Find 160% of ans. a. 18 b. 62.5% c. 5 d #9. ENERGY Complete the graph to show what percent of the total US energy produced was provided by each source in 200. Renewable 12% Nuclear 11% Coal 1% Naturgal gas 29% Petroleum 17% Source: Energy Information Administration

4 #0. GREENHOUSE EFFECT Complete the graph to show what percent of the total US emissions from human activities in 2002 came from each greenhouse gas? Carbon dioxide 8% Nitrous oxide 6% Methane 9% PFCs, HFCs 2% Source: The World Almanac #1. CHILD CARE After the first day of registration, 8 children had been enrolled in a new daycare center. That represented 70% of the available slots. What was the maximum of number of children the center could enroll? 8 is 70% of maximum number of children the center could enroll. Let n be the maximum number of children the center could enroll. Then

5 8 is 70% of n 8 70% n 0. 7n n The maximum number of children the center could enroll is 120. #2. RACING PROGRAMS One month before a stock care race, the sale of ads for the official race program was slow. Only 12 pages, or just 60% of the available pages, had been sold. What was the total number of pages devoted to advertising in the program? 12 is 60% of the total number of pages devoted to the ad program. Let n be the total number of pages devoted to the ad program. Then 12 is 60% of n 12 60% n n The total number of pages devoted to the ad program is 20 pages. #. GOVERNMENT SPENDING The illustration shows the breakdown of ferderal spending for fiscal year 200. If the total spending was approximately $1, 800 billion, how many dollars were spent on Social Security, Medicare, and other retirement programs? Law enforcement and general government % Social Security, Medicare, and other retirement 7% National defense, veterans, and foreign affairs % Physical, human, and community development 10% Social Programs 21% Net interest of the debt 7% 7% of 1, 800 billion is spent on Social Security, Medicare, and other retirement programs. Let A be the amount spent on Social Security, Medicare, and other retirement programs. Then A 7% of 1, 800 7% 1, billion. #. GOVERNMENT INCOME Complete the table by finding what percent of total federal governement income each source provided in 200. Round to the nearest percent. Then complete the circle graph on the next page. 5

6 Total income, fiscal year 200: $2, 200 billion Source of income Amount Percent of total Social Security, Medicare, Unemployment $726 billion Personal income taxes $81 billion 12 Corporate income taxes $12 billion Excise, estate, customs taxes $15 billion 15 Borrowing to cover deficit $7 billion % % % % % 7 % % % 7% % 6% % 7% % 17% #5. THE INTERNET The messahe at the bottom of the computer screen indicate that 2% of of the 50K bytes of information that the user has decided to view have been downloaded to her computer. How many more bytes of information must be downloaded? (50K stands for 50, 000). #6. REBATES A long-distance telephone company offered its customers a rebate of 20% of the cost of all long-distance calls made in the month of July. One customer s call are listed in the table. What amount will this customer receive in the form of a rebate? Date Time Place called Min Amount Jul :8pm Denver 7 $. 80 Jul 9 12:00pm Detroit 68 $7. 50 Jul 20 8:59am San Diego 70 $9. 5 #7. PRODUCT PROMOTIONS To promote sales, a free 6-ounce bottle of sha,poo is packaged with every large bottle. Use the information on the package to find how many ounces of shampoo that large bottle contains. #8. NUTRITION FACTS The nutrition label on a package of corn chips is shown (g stands for grams and mg stands for milligrams.) 6

7 a. How many milligrams of sodium are in one serving of chips? b. According to the label, what percent of the daily value of sodium is this? c. What daily value of sodium intake is deemed healthy? #9. DRIVER S LICENSES On the written part of this driving test, a man answered 28 out of 0 questions correctly. If 70% correct is passing, did he pass the test? #50. THE ALPHABET What percent of the English alphabet do the vowel a e i o and u make up? (Round to the nearest 1 percent)? #51. MIXTURES Complete the table to find the number of gallons of sulfuric acid in each of two storage tanks? Gallons of solution in tank % sulfuric acid Gallons of sulfuric acid in tank Tank % Tank 2 0 0% #52. CUSTOMER GUARANTEES To assure its customers of low prices, the Home Clud offers a "10% Plus" guarantee. If the customer finds the same item selling for less somewhere else, he or she receive the difference in price, plus 10% of the difference. A woman bought miniblinds at the Home Club for $120 but later saw the same blinds on sale for $98 at another store. How much can she expect to be reimbursed? 7

Practice Test for Chapter 4 Ratios and Proportions. a. A is a comparison of two quantities that have different units.

439 Name Date Practice Test for Chapter 4 Ratios and Proportions 1. Use rate or ratio to complete the following statement: a. A is a comparison of two quantities that have different units. Not required