Growth and Decay Apply

1. OPEN ENDED Give an example of a quantity that grows or decays at a fixed rate. Write a real­world problem involving the rate and solve by using logarithms.
2. Writing in Math Use the information about car values on page 564 to explain how you can use exponential decay to determine the current value of a car. Include a description of how to find the percent decrease in the value of the car each year and a description of how to find the value of a car for any given year when the rate of depreciation is known.

GET READY for the Lesson
Certain assets, like homes, can
appreciate or increase in value over
time. Others, like cars, depreciate
or decrease in value with time.
Suppose you buy a car for $22,000
and the value of the car decreases
by 16% each year. The table shows
the value of the car each year
for up to 5 years after it
was purchased
Years after
Purchase
0
1
2
3
4
5
Value of
Car ($)
22,000.00
18,480.00
15,523.20
13,039.49
10,953.17
9200.66