Name: ____________________________________
Date: __________________
Introduction to Percent Algebra 1
Exercise #1: In her math class, Samantha’s two most recent quiz grades are
quiz grade represents the better score? 29 22 and . Which 35 26
A percent is a ratio between two quantities in which the second quantity is always 100. 84% means 84 , or 0.84. You need to have a solid working knowledge of percents, not only for success in this 100 course, but also because percents are used in so many areas in our lives outside of school, such as sports statistics, taxes, wage increases, and sales commissions. Because finding a percent involves work with equivalent fractions, many percent questions are easily handled by solving a proportion of the following type:
Note: It may be helpful to think of the ratio “part/total” as “is/of.” The whole is often preceded by the word “of” in the problem. The part (or percentage) often precedes the word “is” in the problem.
part percent = total 100
Exercise #2: Answer each of the following questions by setting up an appropriate proportion and solving for the unknown. Round answers to the nearest tenth, where appropriate.
(a) What number is 18% of 200? (b) 42 is what percent of 98?
(c) 6% of 240,000 is what number?
(d) 12% of what number is 1044?
Algebra 1, Unit #9 – Measurement – L1 The Arlington Algebra Project, LaGrangeville, NY 12540
Answer each of the following exercises by setting up and solving an appropriate proportion.
Exercise #3: Tanisha is about to sell her house for $315,000. Her real estate broker will expect to receive a 6% commission for all of her hard work in finding Tanisha a buyer for her house. How much money will the real estate broker expect to be paid once Tanisha’s home is sold?
Exercise #4: At South High School, 91 ninth grade students will take the Integrated Algebra 1 state exam this year. If South High School has 142 ninth grade students, what percent of them will be taking the Integrated Algebra 1 state exam? Round your answer to the nearest percent.
Exercise #5: A survey of teenagers from a certain town ages 14 to 18 was taken to see how typical it is for a teenager from that town to carry a cell phone. 88 of the teens surveyed responded that they do carry a cell phone, which represented 80% of the total number of teens surveyed. How many teens were surveyed?
Exercise #6: In a recent basketball game, James made 13 of the 17 foul shots that he took, while Jordan made 15 of the 20 foul shots that he took. Who had the better day from the foul line? Justify your answer.
Exercise #7: Quinn decided to raise all of the prices in his store by 4%. What is the new price of an $8.25 item after the 4% increase?
Exercise #8: Keith plans to buy a car for $21,000. If the sales tax rate for Keith’s town is 8.25%, how much money does he have to pay in taxes on the car?
Algebra 1, Unit #9 – Measurement – L1 The Arlington Algebra Project, LaGrangeville, NY 12540
Name: ____________________________________
Date: __________________
Introduction to Percent Algebra 1 Homework Skills
Use proportions to find the indicated percentage. 1. 4% of 1200 2. 35% of 84 3. 6.2% of 850
4. 25% of 80
5. 40% of 625
1 6. 12 % of 256 2
Use proportions to find the unknown quantity. 7. 32 is 10% of what number? 8. 15% of what number is 30?
9. 200% of what number is 350?
10. 150 is 75% of what number?
Use proportions to find each percent. 11. What percent of 272 is 34? 12. 29 is what percent of 145?
13. 25 is what percent of 20?
14. 37 is what percent of 100?
15. 48 is what percent of 48?
16. What percent of 1200 is 360?
Algebra 1, Unit #9 – Measurement – L1 The Arlington Algebra Project, LaGrangeville, NY 12540
Applications
17. After eating a meal at a restaurant, it is appropriate to leave a 15-20% tip for the waiter or waitress. If your total bill at a restaurant comes to $118.00, what should your tip be if you decide to leave (a) 15%? (b) 20%
18. How much silver is in 125 grams of an alloy that is 12% silver? Give your answer in grams.
19. Devon bought a bike for $279.00. The sales tax rate is 8.25%. (a) Find the total amount of sales tax, in dollars and cents, that Devon is required to pay.
(b) Find the amount that Devon has to pay for the bike including sales tax.
20. In a factory, 4150 parts were made on a given day, and 4% of those parts were found to be defective. How many of the parts were not defective?
Reasoning
21. Sheila claims that if you increase a number by 10% and then decrease the result by 10%, you are right back where you started. Show that Sheila is incorrect by using a specific numerical example.
Algebra 1, Unit #9 – Measurement – L1 The Arlington Algebra Project, LaGrangeville, NY 12540