Lesson 8
Section two
Complete the following
questions. Use your notes from
lesson 8 – exponential growth
and decay. Continue to write your
answers on the answer sheet
from lesson 8 – section 1.
Exponential Growth and Decay
GROWTH
DECAY
When the amount increases by
the same percent for each time
period
A =I(1+r)
t
When the amount decreases by
the same percent for each time
period
A =I(1-r)
t
QUESTIONS:
1. What are the formulas for exponential
growth and decay?
Using the exponential formulas, what
does 1 + r or 1 –r become for each
problem below?:
2. A $10,000 investment decreased by 3%
each year for 5 years.
3. A city population of 200,000 increases 4%
each year for 10 years.
Complete the following questions below.
Decide which formula to use: simple
interest, compound interest, exponential
growth or decay.
4.Jessica deposits $4,000 in a savings account
that pays interest at 6.5% a year. How much will
the investment accumulate to after 1 year?
5. $7,563 is invested at 6.2% compounded
annually for 10 years. How much money will the
investment yield after 10 years? Round to the
nearest penny.
Find the yield, to the nearest penny,
of each investment:
6. A principal of $20,000 is invested at 6%
compounded annually for 4 years.
7. A principal of $40,000 is invested at 4.9%
compounded annually for 5 years.
8. A principal of $35,000 is invested at 4.5%
compounded annually for 4 years.
Solve. Round answers to the
nearest whole number.
9. A business earned $200,000 in 1997. If it is
predicted that the earnings will increase by 3%
every year, predict the earnings at the end of 10
years.
10. A biologist discovers that a certain bacteria has
a growth rate of 4% every hour. There are
currently 15,000 bacteria. Predict the number at
the end of 6 hours.
• Your homework is a worksheet. Complete
all of the problems.