Exponential Models

Which of the following is an exponential decay model?

• $y=3000\left(-2\right)^x$

• $y=2\left(1.04\right)^x$

• $y=-\frac{3}{2}x-7$

• $y=40\left(0.79\right)^x$

Consider the exponential growth equation $y=5678\left(1.60\right)^x$  

What is the initial value?

Which of the following is the correct multiplier for an exponential model with a 45% rate of growth?

• 1.45

• 0.45

• 1.045

• 45

Check all equations that are exponential models.

• $y=2\left(4\right)^x$

• $y=2\left(1\right)^x$

• $y=2\left(-1.01\right)^x$

• $y=2\left(0.5\right)^x$

• $y=3x^2-7$

Which of the following is the correct multiplier for an exponential model that decreases at a rate of 5%?

• -0.05

• 0.05

• 0.95

• -5

Choose the correct model:

Jo invests $500 in an account that earns 1.17% interest annually.

• $y=500\left(1.17\right)^x$

• $y=1.17\left(500\right)^x$

• $y=500\left(x\right)^{1.17}$

•  $y=500\left(1.0117\right)^x$ 

Choose the correct equation to solve:


There are initially 12 bacteria in a petri dish. The number of bacteria double every hour. How many bacteria would there be after 10 days?

•  $y=12\left(2\right)^{10}$  

•  $y=12\left(2\right)^{240}$  

•  $y=12\left(10\right)^2$  

•  $y=2\left(12\right)^{240}$  

Choose the correct model to represent the value of an iPhone purchased in 2012:

A new iPhone cost $599 in 2012. It loses 34% of its value each year after 2012.

• $y=599\left(0.66\right)^x$

• $y=599\left(0.34\right)^{2012}$

• $y=599\left(1.34\right)^x$

• $y=2012\left(5.99\right)^{34}$