Algebra 2H
Key- Review- Exponential Functions Test
Name:____________________________________
Date:_____________________________________
Simplify:
1.
2.
3.
4.
Solve:
5.
6.
7.
8.
9.
10.
11.
12.
1
13.
The Franklins inherited $3,500, which they want to invest for their child’s future college expenses. If
they invest it at 8.25% with interest compounded monthly, determine the value of the account, in dollars,
after 5 years.
14.
Akeem invests $25,000 in an account that pays 4.75% annual interest compounded continuously. How
many years, to the nearest tenth, will it take for Akeem’s investment to triple?
15.
Aidan invests $5000 in an account that earns 3.5% interest compounded annually. What is the total
amount of his investment after 3 years?
16.
Ariana has a choice of two investments. She can invest $10,000 at 5% for 6 years or she can invest
$9,000 at 6.5% for 7 years. Both accounts are compounded annually. Which investment will result in a
greater amount of interest earned?
17.
Jack buys a tractor for $18,000 for his farm. The tractor depreciates 12% every year. What will his
tractor be worth in 10 years?
2
18.
In 1970, a candy bar cost $.25. If the rate of inflation was 3% every year, how much should the candy
bar cost today?
19.
Jess wants to buy a car but she cannot decide if she should buy a Honda or a Kia. The Honda costs
$16,000 and depreciates at an annual rate of 8%. The Kia costs $12,000 and depreciates at an annual
rate of 12%. What will each car be worth in 5 years? In 10 years? Which car should she buy and why?
20.
Mark bought a house in 1995 for $200,000. His house has appreciated 4% every year since he bought
it. How much is his house worth today?
21.
Lucy’s mom started a savings account for Lucy to go to college when she was 5 years old. She put
$1000 into an account that earned 6% interest. Lucy is now 18. How much money does Lucy have?
22.
When a certain drug enters the blood stream, it gradually dilutes, decreasing exponentially with a halflife of 3 days. The initial amount of the drug was 64 milligrams.
a) Write the equation of this function.
Show all work!
b) Determine the amount of the drug left in the blood stream after 15 days.
3
23.
A dish has 212 bacteria in it. The population of bacteria will grow by 80% every 2 days. How many
bacteria will be present in . . .
a) 4 days
24.
b) 36 hours
c) 2 weeks
In June, a 5th grade class started out with 10 mealworms for an experiment. The population of worms
will double (grow by 100%) every month. How many mealworms will the class have for their
experiment in . . .
a) 3 months
26.
c) 11 days
The house down the street has termites in the porch. The exterminator estimated that there are about
800,000 termites eating at the porch. He said that the treatment he put on the wood would kill 40% of
the termites every day. How many termites will be eating at the porch in . . .
a) 3 days
25.
b) 8 days
b) 1 year
c) 45 days
Your baby brother has an ear infection. The doctor said there are probably 50,000,000 bacteria in his
left ear. The penicillin the doctor prescribed will kill 7% of the bacteria every 6 hours. How many
bacteria will be in your brother’s ear in . . .
a) 1 day
b) 3 hours
c) 1 week
4
27.
Tim is saving up for a vacation. He decides to put $135 each month into an account earning 1.05%
interest compounded monthly. How much will he have in his account at the end of a 5-year period?
Round to the nearest hundredth.
28.
Jim is also saving up for a vacation. He decides to put $135 each month into an account earning 1.05%
interest compounded continuously. How much will he have in his account at the end of a 5-year period?
Round to the nearest hundredth.
29.
Repeat both #27 and #28 using an interest rate of 1.1%. What is the difference in total interest earned?
30.
There are 20 fish living in Logarithm Lake on June 1, 2003. On June 1, 2007, the population had
tripled. Write an exponential function model that can be used to express the number of fish living in
Logarithm Lake at any time t. Graph this function on [0,10]. What is the total number of fish living in
Logarithm Lake on December 1, 2014?
5