Exponential Decay - decreases by a constant factor

-decay factor (Mult.)- Less than 1

X Y1 100

2 20 3 4

d.f. =

Y-int =

Decay Rate• % data is decreasing by

EXAMPLEIf you are given the decay factor 0.52

- Make a % 52% - Subt from 100 = decay rate 48%

If you are given the decay rate 87% - Subt from 100 13 % - Make a decimal = decay factor .13

Exponential Decay

X Y x y 0 300 0 324 1 180 1 1082 108 2 36

DF = DF =

Unit Review

GGG

Round 1

The foundation of your house has about 1,200 termites. The termites grow at a rate of about 15% per day.

1. Growth Factor?

2. Write an equation

Round 2

1. How many termites will there be in 3 weeks?

2. When will there be 850,000 termites?

y=1200(1.15x)

Round 3

1. What is the decay rate?

2. What is the decay factor?

Kristen saved $5000, but in order to pay bills she is spending her money at a rate of 40% of her savings per month.

Round 4

• Kristen saved $5000, but in order to pay bills she is spending her money at a rate of 40% of her savings per month.

Months 0 1 2 3 4 CurrentBalance

Round 5

• Kristen saved $5000, but in order to pay bills she is spending her money at a rate of 40% of her savings per month.

1. Write an equation.

2. When will she run out of money?

• The Easter bunny gave Tommy 5 jellybeans and sent him on a hunt for the rest. He finds 10 jellybeans per min.

–What type of relationship is this?

-Write an equation that represents the total number of jellybeans Tommy has.

• Joey collected 85 jellybeans. He does not like the black jellybeans, so he threw them at his brother at a rate of 6 jellybeans per min.

-Write an equation that represents how many jellybeans Joey has.

-In 14 min, how many does Joey have left?

Round 6

• Find the decay rate or factor1. 20%

2. 0.85

3. 0.7

4. 54%

Round 7

• You drink a Pepsi that contains 120mg of caffeine . Each hour, the caffeine decreases by 12%.

1. What is the decay rate?

2. What is the decay factor?

3. Write an equation

Round 8

An adult takes 400 mg of ibuprofen. Each hour, the amount of ibuprofen in the person’s system decreases by about 29%. How much ibuprofen is left after 6 hours?

Round 9

• You have inherited land that was purchased for $30,000 in 1960. The value of the land increased by approximately 5% per year. What is the approximate value of the land in the year 2011?