1. Warm Up In the textbook… p. 436 #1 – 3 Read directions about x values!

2. Questions ?

3. Exponential Growth Starting Amount (when x = 0) Growth Factor

4. b = 100% + rate of growth

5. Writing an Equation for Exponential Growth 1.A new automobile currently cost $17,000. The cost increase 5% per year.

6. Writing an Equation for Exponential Growth 2.The cost of tuition at a college is $12,000 and is increasing at a rate of 6% per year.

7. Writing an Equation for Exponential Growth 3.The population of a city of 450,000 people increases 2.5% per year.

8. Writing an Equation for Exponential Growth 4.The number of student-athletes at West Johnston High School is 300 and is increasing at a rate of 8% per year.

9. Practice! In the Practice Workbook… Reteaching 8-8 (p. 109) # 1 – 3

10. Assignment In the textbook… p. 441-442 # 1 – 10, 31, 35

11. Warm Up In the Practice Workbook… Practice 8-8 (p. 110) #1, 3, 5

12. Questions ?

13. Compound Interest Objective: To learn use exponential growth to calculate compound interest. simple interest – interest paid only on the principal. I = p ∙ r ∙ t Principal (amount invested) Interest Rate (as a decimal) Time (in years) Interested Earned

14. Compound Interest  interest paid on both principal and the interest that has already been earned

15. Example 1 You invest $5000 in an account paying 6% compounded annually. Find the account balance after each of the following years. a) 1 yrb) 5 yrc) 10 yrd) 20 yr

16. Example 2 You invest $2500 in an account paying 7.25% compounded annually. Find the account balance after each of the following years. a) 1 yrb) 2 yrc) 6 yrd) 25 yr

17. Example 3 You invest $28,000 in an account paying 4% compounded annually. Find the account balance after each of the following years. a) 1 yrb) 2 yrc) 5 yrd) 15 yr

18. Compound Interest Over the year you have options on how many times during the year the amount is calculated! CompoundedPeriods Per Year annually1 semi-annually2 quarterly4 monthly12 daily365

19. Example 4 “semi-annually” You invest $5000 in an account paying 6% per year (APR). Find the account balance after 15 years with the interest compounded semi-annually.

20. Example 5 “quarterly” You invest $5000 in an account paying 6% per year (APR). Find the account balance after 15 years with the interest compounded quarterly.

21. Example 6 “monthly” You invest $5000 in an account paying 6% per year (APR). Find the account balance after 15 years with the interest compounded monthly.

22. Example 7 “daily” You invest $5000 in an account paying 6% per year (APR). Find the account balance after 15 years with the interest compounded daily.

23. Formula for Compound Interest Principal (amount invested) Total Amount Earned Number of periods per year Time (in years) Interest Rate (as a decimal)

24. Assignment Calculating Compound Interest Worksheet