Name: ______________________________________________________ Date: ______________ Period: _______
A2 Exponential Functions
Write an exponential function to model each situation. Find the value of the function after 8 years.
1. A $12,000 car depreciates 25% each year.
3. A population of 2785 brown bears increases 3%
each year.
2. A $22,000 truck depreciates 12% per year.
4. A $45,000 investment increases at a rate of
9.8% per year.
5. The population of the animals you are studying is decreasing by 1.5% each year. There were about 2,000,000 of
them world-wide this year.
Identify each function as modeling either exponential growth or exponential decay. What is the percent of increase or
decrease for each function?
6. 𝑦 = 72(1.6)𝑥
8. 𝑦 = 2.02(2.01)𝑥
7. 𝑦 = 24(0.8)𝑥
9. 𝑦 = 0.9(0.92)𝑥
Solve:
10. Suppose you have 1 g of a mixture that is losing 1% of mass each hour by evaporation.
a. What is the decay factor of the mixture?
b. Write an equation to model the mass of the mixture.
11. In 1985, there were 285 cell phone subscribers in the small town of Centerville. The number of subscribers
increased by 75% per year after 1985. How many cell phone subscribers were in Centerville in 1994?
12. The population of Winnemucca, Nevada, can be modeled by 𝑃 = 6191(1.04)𝑡 where t is the number of years
since 1990. What was the population in 1990? By what percent did the population increase by each year?
13. You have inherited land that was purchased for $30,000 in 1960. The value of the land increased by
approximately 5% per year. What is the approximate value of the land in the year 2014?
14. An adult takes 400 mg of ibuprofen. Each hour, the amount of ibuprofen in the person’s system decreases by
about 29%. How much ibuprofen is left after 6 hours.