Transcript Exponential Growth and Decay

Exponential Growth
and Decay
Objective:
To model exponential growth and decay

The basic exponential function is y  a  b x where
a represents the initial amount
b represents the growth (or decay) factor.
The growth factor equals 100% plus the percent rate of change.
The decay factor equals 100% minus the percent rate of decay.
x represents the number of times the growth or decay factor
is applied
y represents the result of applying growth or decay factor
x times
Exponential functions

1.
Since 2005, the amount of money spent at
restaurants in the United States has increased about 7%
each year. In 2005, about $360 billion was spent at
restaurants. If the trend continues, about how much will
be spent at restaurants in 2015?
EX: Model Real-life situations

2.
A family buys a car for $20,000. The value of the car
decreases about 20% each year. After 6 years, the family
decides to sell the car. What is the value of the car?
EX: Model Real-life situations

3. A population of 100 frogs increases at an
annual rate of 22%. How many frogs will there
be in 5 years?
EX: Model Real-life situations

4. The population of a city is 45,000 and
decreases 2% each year. If the trend continues,
what will the population be after 15 years?
EX: Model Real-life situations
Exponential growth and
decay worksheet
10 questions