Download Unit 6-7a – Exponential Growth and Decay

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