Exponential growth & decay

1. Mod 7 Lesson 6 Review

3. Remember, to find your
growth or decay factor:
b = 1 + rate
Rate must be written as a decimal.
From % to decimal, you will need to move
the decimal 2 places to the left.
For example, 6.8% would be 0.068.

4. If the value of the house
is decaying at 37%, our
decay factor would be:
b=1-.37=.63
If a population is growing
at 7%, our growth factor
would be: b=1+.07 = 1.07

5. On your 10th birthday, you invested $235 in an
account that pays 7.5% annually. You are
planning to withdraw the money on your 18th
birthday.
How much money will be in the account?
• Initial amount: a=235
• Rate as a decimal: r=.075
• Growth factor: b=1+.075=1.075
• Time: t=8
𝑦 = 235(1.075)8
= $419.12