2. Lesson Menu Main Idea and New Vocabulary NGSSS Example 1:Find Simple Interest Example 2:Find the Interest Rate Example 3:Find the Total Amount Five-Minute Check

3. Main Idea/Vocabulary Solve problems involving simple and compound interest. interest simple interest principal compound interest

4. NGSSS MA.8.A.6.4 Perform operations on real numbers (including integer exponents, radicals, percents, scientific notation, absolute value, rational numbers, and irrational numbers) using multi-step and real world problems.

5. Example 1 Find Simple Interest Find the simple interest for $2,000 invested in a savings account at 5.5% for 4 years. I = prt Write the simple interest formula. I = 2,000 ● 0.055 ● 4 Replace p with 2,000, r with 0.055, and t with 4. I = 440 Answer: The simple interest is $440.

6. Example 1 CYP A.$44.10 B.$132.30 C.$1,112.30 D.$1,323.00 Find the simple interest for $980 invested in a savings account at 4.5% for 3 years.

7. Example 2 LOANS Callie borrowed $4,500 from a bank to pay part of her college tuition. She will repay the loan by paying $120 a month for the next four years. Find the simple interest rate of the loan. Find the Interest Rate First find the total that Callie will pay. $120 ● 48 = $5,760 4 years = 48 months She will pay $5,760 – $4,500 or $1,260 in interest. So, I = 1,260.

8. Example 2 Find the Interest Rate I= prt Write the simple interest formula. 1,260= 4,500 ● r ● 4 Replace I with 1,260, p with 4,500, and t with 4. 1,260= 18,000r Simplify. 0.07= rSimplify. Answer: The simple interest rate is 0.07 or 7%. Divide each side by 18,000. 1,260

9. Example 2 CYP A.1.18% B.6% C.6.6% D.18% LOANS Samantha borrowed $7,200 from a bank to pay for a used car. She will repay the loan by paying $236 a month for the next three years. Find the simple interest rate of the loan.

10. Example 3 Find the Total Amount SAVINGS How much money is in an account where $80 is invested at an interest rate of 6% compounded annually for 3 years? Find the amount of money in the account at the end of the year 1. I= prt Write the simple interest formula. I= 80 ● 0.06 ● 1 Substitution I= 4.8 Simplify. 80 + 4.80 = 84.80 Add the amount invested and the interest.

11. Example 3 Find the Total Amount Find the amount of money in the account at the end of year 2. I= prt Write the simple interest formula. I= 84.80 ● 0.06 ● 1 Substitution I= 5.088 Simplify. 84.80 + 5.09 = 89.89 Add the amount invested and the interest.

12. Example 3 Find the Total Amount Answer:After 3 years there is $89.89 + $5.39 or $95.28. Find the amount of money in the account at the end of year 3. I= prt Write the simple interest formula. I= 89.89 ● 0.06 ● 1 Substitution I= 5.3934 Simplify.

13. Example 3 CYP A.$327.05 B.$345.04 C.$361.15 D.$364.02 SAVINGS How much money is in an account where $310 is invested at an interest rate of 5.5% compounded annually for 3 years?

14. A.$8.00 B.$12.00 C.$24.00 D.$240.00 Find the simple interest to the nearest cent. $300 at 4% for 2 years Five Minute Check 1

15. A.$23.44 B.$37.50 C.$46.88 D.$234.38 Find the simple interest to the nearest cent. $750 at 6.25% for 6 months Five Minute Check 2

16. A.$1,337.50 B.$1,425.00 C.$1,431.13 D.$2,675.00 Find the total amount in the account to the nearest cent if the interest is compounded annually. $1,250 at 7% for 2 years Five Minute Check 3

17. A.$628.50 B.$642.75 C.$643.43 D.$942.75 Find the total amount in the account to the nearest cent if the interest is compounded annually. $600 at 4.75% for 18 months Five Minute Check 4

18. A.$110.00 B.$550.00 C.$610.50 D.$1,100.00 Sam borrowed $5,000 at 11% simple interest for two years. He made no payments during those two years. How much interest is owed at the end of those two years? Five Minute Check 5

19. A.$18.75 B.$37.50 C.$187.50 D.$225.00 Anna decided to invest $1,500 at 2.5% simple interest for six months. How much interest does her investment earn? Five Minute Check 6