# Algebra 1 i Chapter 9 Test ```Algebra: Exponential Unit Review Packet
1.
Name___________________________________
p  1000 1.25
t
A colony of bacteria grows according to the equation:
where p is the population after t hours.
What will the population be in 4 hours?
What was the population 4 hours ago?
What is the rate of growth for this colony of bacteria?
2.
Match each description with its graph:
________i.
Linear increase (growth)
________ii.
Linear decrease (decay)
________iii.
Exponential increase (growth)
________iv.
Exponential decrease (decay)
________v.
A
D
E
C
B
3.
A car costs \$15,000 and loses 18% of its value every year.
Write an equation expressing the value of the car in t years.
How much will the car be worth in 5 years?
4.) You put \$4000 in an account that earns 3.5% interest each year.
a.) Write an equation.
b.) How much money will you have in 10 years?
5.) There are currently 25000 people in a town that has been growing by 12% each year.
a.) Write an equation.
b.) How many people will there be in 2022?
c.) How many people were there in 2000?
6.) Trumaine had \$285, but he lost \$15 every day until he had no money left. For how many
days did he lose money?
7.) There are currently 3200 students at ETHS, but the population is decreasing by 6% per year.
a.) Write an equation.
b.) How many students will there be in 20 years?
8. Change to scientific notation:
a. 16 billion
9.
b. .000062
Once Whitney was using a friend’s calculator.
She correctly found this answer on the machine’s screen:
4.628345 E 6
Is this answer between 4 and 5? ___________
If “NO,” then name two numbers that her answer falls between:
10.
A sad teacher I know has an investment portfolio that has lost money for the last 3 years.
When it started, the value was about \$30,000.
It has lost 6% per year during that time.
What is the value of this investment today?
11.
The amount of lead in a person’s body falls by the same percentage rate
each day after that person has swallowed the lead contaminant.
Which graph below shows how the amount of lead changes over time? ____________
A
B
time
C
time