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Algebra 2, Algebra 2 – Unit 6-7 Name: ________________________________ Date: ________________ Period: _______ Unit 6-7a – Exponential Growth and Decay - Practice 1. A $22,000 truck depreciates 11% per year. Write an exponential function to model the situation. Find the value of the function after 8 years. Round to the nearest cent. 2. A population of 2785 brown bears increases 3% each year. Write an exponential function to model each situation. Find the value of the function after 8 years. Round to nearest integer (whole bear). 3. If you invest $2000 compounded annually at 6%, how long will it take to double your investment? Round to 3 decimal places. 4. Suppose you deposit $1000 in an account paying 3% annual interest, compounded continuously. Using A Pe r t , find the balance after 10 years. Round to the nearest cent. 5. Suppose your savings account balance is currently $5,200 in an account paying 5% annual interest, compounded continuously. Using A Pe r t , calculate how much money you deposited when you first opened the account 18 years ago. Round to the nearest cent. Algebra 2, Algebra 2 – Unit 6-7 6. (a) A bacteria doubles every 7 hours. The biologist has 48 bacteria now. How many will there be in 42 hours? (b) When will there be 1200 bacteria remaining? Round to 3 decimal places. 7. A chemical substance has a half-life of 5 hours. (a) How much of a 12-gram sample remains after 12 hours? Round to 3 decimal places. (b) When will there be only 3 grams remaining? 8. Jeanine bought a car 8 years ago for $18,000. The car is now worth $3,500. Assuming a steady rate of depreciation, use A a(1 r )t to find the yearly rate of depreciation (express as a percent with 1 decimal place). Algebra 2, Algebra 2 – Unit 6-7 Answers: 1. $8,660.50 2. 3528 bears 3. 11.896 years 4. $1,349.86 5. $2,114.16 6. a) 3072 bacteria b) 32.507 hours 7. a) 2.274 grams b) 10 hours 8. 18.5% depreciation per year