Exponential Growth and Decay

If the decay rate is 20%, which of the following represent the decay factor?

• 0.2

• 0.8

• 1.2

• 1.8

If the growth rate is 80%, what is the growth factor?

• 0.2

• 0.8

• 1.2

• 1.8

 A flea medicine breaks down at a rate of 20% per hour.  This is the rate of decay of the medicine. The initial dose is 60 milligrams. Which of the following represent the equation the models the amount of flea medicine left in an animal?

•  $y=60\left(.2\right)^x$  

•  $y=20\left(60\right)^x$  

•  $y=60\left(.8\right)^x$  

•  $y=60\left(1.2\right)^x$  

The value of a car depreciates exponentially. Identify the decay factor is the car was worth $20,000 initially and worth $15,000 after 1 year.

• 1.33

• 0.75

• 0.66

• 0.25

Select all the equations that represent exponential decay.

• $y=\frac{1}{2}\left(4\right)^x$

• $y=4\left(\frac{1}{2}\right)^x$

• $y=80\left(1.4\right)^x$

• $y=60\left(0.7\right)^x$

• $y=3\left(0.6\right)^x$

Find the decay factor from the given graph.

• $3$

• $1$
  

• $\frac{1}{3}$

• $\frac{1}{9}$

Jack invest $600 earning 5% interest rate. How much will he have after 5 years?

• $630

• $729.30

• $765.77

• $4556.25