Mastering Percentages: Key Concepts and Problem Solving for Your Test

1. Ch. 7-Percents Review Test Wednesday! Study! Study! Study!

2. Vocabulary Percent: Is a ratio in which the first term is compared to 100. Discount: The amount to be taken off the original price. Principal: An amount of money borrowed or loaned. Interest: A charge for the use of money, paid by the borrower to the lender. Simple Interest:Interest paid only on the principal

3. Equating Percents with Fractions and Decimals Describe the shaded region as a fraction, decimal and percent. 38= X • 100 X=38% 38 = .38 100

4. Describe the shaded region as a fraction, decimal and percent. Fraction:______ Decimal:______ Percent: ______

5. Finding the Percent of a Number using Mental Math *Change the percent to a fraction that can easily be divided into the whole number. Ex. 80% of 40 is ____. 4 × 40 = 32 5

6. Find the Percent of a number using Mental math 1.) 20% of 50 2.) 25% of 60

7. Estimating the Percent of a Number *Change the percent into a fraction. Then change the whole number into one that can be easily divided by the fraction. Ex. 71% of 62 70% of 60 70 × 60 = 42 100

8. Estimating the Percent of a Number 1.) 42% of 367 2.) 34% of 55

9. Finding the Exact Percent of a Number *Remember that the “Of” number goes on the bottom. Is of Ex. 19% of 184 19 = X • 184 X=34.96 19% of 184 is 34.96.

10. Ex 2- 32% of _____ is 57.6. 32 = 57.6 100 X 32X=5,760 X=180 32% of 180 is 57.6.

11. Find the Exact Percent of a Number 1.) 25% of 16 2.) 55% of 750 3.) 64% of _____is 208. 4.) 28% of _____is 43.4

12. Sales Tax and Discounts *Find the percent of a number. Tax-add it back to the original number. Discount-subtract it from the original number.

13. Example: Discounts Kyung wants to buy a skirt from Hollister for $47.50. it is discounted 20%. What is the end price of the skirt? 20% of $47.50 $47.50-9.50=$38.00 20 = X • 47.50 100X=950 X=$9.50 (discount)

14. Example: Sales Tax Michael wants to buy a shirt from Zumez for $36.99. The sales tax is 5%. What is the end price? 5% of $36.99 $36.99+1.85=$38.84 5 = X • 36.99 100X=184.95 X=$1.85 (Sales tax)

15. 1.) Noa wants to buy a pair of earrings for $14.95. The earrings are discounted 10%. What is the end price?

16. 2.) Ross wants to buy the new Mortal Combat video game at Gamestop for $59.99. The sales tax is 6.5%. What is the end price?

17. Percent Increase or Decrease X = Difference between two amounts • Original Number Ex. Izzi wants to buy a pair of shoes that originally cost $48. The shoes are on sale and now cost $35. What is the percent decrease? $48-35=13 X = 13 • 48 48X=1300 X=27.1%

18. 1.) There are 14 people in class on Tuesday. There are 20 people in class on Wednesday. What is the percent increase?

19. 2.) Ms. Nelson also works at Express and receives a store discount. She bought a $75 skirt for $60. What is the percent decrease?

20. Simple Interest Interest = Principal × Rate × Time I = P × r × t Total =Principal +Interest T=P+I

21. Simple Interest Ex. Megan borrowed $12, 000 for 1 year at a simple interest rate of 6.75% per year. Find the amount of interest and the total amount. I=P×r×t T=P+I I=12,000×.0675×1 T=$12,000+810 T=$12,810 I=12,000×6.75×1 100 I=$810

22. 1.) Carrington invests $15,000 for 8 years at a simple interest rate of 6.75% per year. Find the amount of interest and the total amount.

23. 2.) Jacob invests $850 at a simple interest rate of 5.5% per year for 5 years. Find the amount of interest and the total amount.