CCGPS Algebra
Exponential Equations
Name
1. You have a bank account. The account starts with $100 and has an annual rate of 4% interest.
a. Write an exponential equation to represent this scenario.
b. Find how much money is in the account after 12 years.
c. How many years do you have to invest the money before you have $250,000?
2. 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.
a. Write an exponential equation to represent this scenario.
b. Find how many subscribers there are in 1994.
c. In what year will there be 5000 subscribers?
3. Bacteria multiplies at an alarming rate splitting into 2 new cells every hour, thus doubling. We begin with 1
bacteria.
a. Write an exponential equation to represent this scenario.
b. Find out how many bacteria you have by the end of the day.
c. How long does it take to have 1 million bacteria?
4. Each year the local country club sponsors a tennis tournament. Play starts with 128 participants. During
each round, half of the players are eliminated.
a. Write an exponential equation to represent this scenario.
b. How many players remain after 5 rounds?
c. After how many rounds will you have 8 players?
5. The population of Winnemucca, Nevada increased by 4% each year. There were 6191 people in the town in
1990.
a. Write an exponential equation to represent this scenario.
b. How many people will be in town in 2010?
c. In what year will there be 10,000 people in Winnemucca?
6. You have inherited land that was purchased for $30000 in 1960. The value of the land increased by
approximately 5% per year.
a. Write an exponential equation to represent this scenario.
b. How much will the land be worth in 2011?
c. In what year will the land be worth $1,000,000?
7. During normal breathing, about 12% of the air in the lungs is replaced after one breath. You start with 500
milliliters of air in your lungs.
a. Write an exponential equation to represent this scenario.
b. How much of the original air is present after 240 breaths?
c. After how long will there only be 1 mL of the original breath in the lungs?
8. An adult takes 400 mg of ibuprofen. Each hour, the amount of ibuprofen in the person’s system decreases
by 29%.
a. Write an exponential equation to represent this scenario.
b. How much of the ibuprofen is left after 6 hours?
c. After how long will there only be 10 mg of ibuprofen in the system?
9. You deposit $1600 in a bank account. The account pays .5% monthly interest.
a. Write an exponential equation to represent this scenario.
b. How much money would you expect to have in 2 years?
c. After how long will you have $10,000?
10. You buy a new computer for $2100. The computer decreases by 50% annually.
a. Write an exponential equation to represent this scenario.
b. How much will the computer be worth after 5 years?
c. When will the computer have a value of $600?