7.2.2 HW
Using Exponential Growth Models
1. In 1980 about 2,180,000 U.S. workers worked at home. During the next
ten years, the number of workers working at home increased 5% per year.
a) Write a model giving the number w (in millions) of workers working
at home t years after 1980.
b) How many workers will be working at home in the year 1988
according to the model?
2. In 1990 the cost of tuition at a state university was $4300. During the next
8 years, the tuition rose 4% each year.
a) Write a model that gives the tuition y (in dollars) t years after 1990.
b) According to the model, what will the tuition be at a state university in
1996?
Using Exponential Decay Models
3. There are 40,000 homes in your city. Each year 10% of the homes are
expected to disconnect from septic systems and connect to the sewer
systems.
a) Write an exponential decay model for the number of homes that still
use septic systems.
b) Use the model to estimate the number of homes using septic systems
after 5 years.
4. A new car costs $23,000. The value decreases by 15% each year.
a) Write an exponential decay model for the car’s value.
b) b. Use the model to estimate the value of the car after 3 years.