This document contains math problems and solutions related to percentages, discounts, interest, ratios, and other concepts. It includes examples such as calculating simple and compound interest on loans, finding the total cost after multiple discounts are applied to a product price, determining the rate of pay per ton based on a ratio, and taking cube roots. The document serves as a review for mathematical concepts involving fractions, percentages, proportions, and operations with integers.

1. Math 8 Unit 2 – Percentage Review

2. Simple Interest Mr. Otto wanted to build a garage. Therefore, he had to borrow money from the bank. He borrowed $7,000 at a rate of 5% for 30 months. What is the amount of interest he had to pay on the loan?

3. Answer – Simple Interest I = Prt I= $7,000(.05)(30/12) I= $875

4. Compound Interest Dr. Winslow wants to open a medical office in Levering but does not have the money to do so. Therefore, he gets a loan from the bank. He borrows 120,000 at an interest rate of 8% which is compounded semi-annually for 9 years. How much will he pay back altogether?

5. Answer – Compound Interest A= P(1 + r/n)n*y A=$120,000(1 + .08/2)2*9 A=$120,000(1+ .04)18 A= $120,000(1.04)18 A= $243,097.98

6. Multiple Discounts A $900.00 Dell Laptop was marked down 25% for a Christmas special. It did not sell on Black Friday so it was marked down another 15%. It still did not sell so it was marked down another 10% and it sold then within an hour. How much did the laptop sell for?

7. Answer – Multiple Discounts Remember use the % it is actually worth – NOT the % discount. $900 (.75)(.85)(.90) $516.38

8. Ratio Units Raymond gets paid $550 for dropping off scrap metal to the junk yard. His scrap totals 2.75 ton. What is the price he is paid per ton of scrap metal?

9. Answer – Ratio Units Price per ton? $550/2.75 ton $200 per ton

10. Simple Interest – Total Amount Gracie needs to borrow $1,000 to buy the dog of her dreams. She borrows the money from Capital Bank at a rate of 6.5% for 5 years. What is the total payback amount?

11. Answer – Simple Interest Total Amount I = Prt I= $1,000(.065)(5) I= $325 $1,000 + $325 = $1,325

12. Multiple Discounts A new Camaro costs $45,000 brand new. The car depreciates in value 22% each year. What will it be worth in 7 years?

13. Answer – Multiple Discounts Remember use the % it is ACTUALLY worth! $45,000(.78)7 $7,904.51

14. Proportions 30 = ______% of 75

15. Answer - Proportions Is/of and %/100% 30/75 n/100% Cross multiple 30 * 100 = 3000 3000 / 75 = 40%

16. % Increase You buy an IPod touch for $258 with 6 % sales tax. What is the total price?

17. Answer - % Increase Always start with 100% 100% + 6% ($258) 106% ($258) 1.06($258) $273.48

18. Simple Interest – Find the Rate What is the simple interest rate for a snowboard that costs $680 with a loan for 2 years and interest of $170?

19. Answer – Simple Interest find the rate Work backwards from I=Prt $170 = $680(r)(2) $170 / $680 / 2 .125 = 12.5%

20. Perfect Squares 42 is between what two perfect squares?

21. Answer – Perfect Squares First find the square root of 42 6.48 so it is between 6 and 7 6’s perfect square is 6 * 6 = 36 7’s perfect square is 7 * 7 = 49 36 & 49

22. Cube Root The cube root of 189 is between what two integers?

23. Answer – Cube Root To find the cube root you need to put the number to the 1/3 power. 5.74 5 & 6

24. Credits All of the images in this review presentation were thanks to Google Images !!