Exponential Functions

Does the graph represent an exponential growth or an exponential decay function?

• Growth

• Decay

What equation represents the balance of a $2,000 deposit that paid 5% interest over 3 years?

• $A=2000\left(5\right)^3$

• $A=2000\left(1+5\right)^3$

• $A=2000\left(1+.05\right)^3$

• $A=2000\left(1+.5\right)^3$

 In the exponential function to calculate compound interest $A=P\left(1+\frac{r}{n}\right)^{nt}$ what does the variable n represent?

• n = time in years

• n = nominal interest

• n = number of compounding periods in a year

• n = root thingie

Does the equation represent exponential growth or decay?

• Growth

• Decay

Calculate the y-intercept for the graph of the exponential function $y=\left(1.35\right)^x$ . 

•  $\left(0,\ 1.35\right)$  

•  $\left(0,\ 1.8225\right)$  

•  $\left(0,\ 0\right)$  

•  $\left(0,\ 1\right)$  

A bacteria culture is started in a petri dish with 1200 organisms. After 4 hours, there are 2400 giving a growth factor of 1.26 from this equation: $2400=1200a^4$  

How many bacteria are expected after 8 hours?

•  $f\left(8\right)=1200\left(1.26\right)^8$  

•  $f\left(8\right)=1200^8$  

•  $1200=1.26^8$  

•  $f\left(8\right)=1.26^8$  

A deposit of $2500 has an interest rate of 4% compounded continuously. What would the balance be after 3 years?

• $A=2500\left(1+0.04\right)^3$

• $A=2500e^3$

• $A=2500e^{0.04}$

• $A=2500e^{\left(0.04\right)\left(3\right)}$

The NCAA Basketball tournament starts with 64 teams. After each round, only half the teams remain. How many teams remain after the 4th round?

P = 64

a = 1/2

x = number of rounds

 $f\left(x\right)=Pa^x$ 

•  $f\left(4\right)=64\left(\frac{1}{2}\right)^4$  

•  $f\left(4\right)=\left(\frac{64}{2}\right)^4$  

•  $f\left(4\right)=64\left(2\right)^4$  

• decay

• growth

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