Unit 5 Review

Write an exponential function to model the table.

Which exponential function best models the following data?

• y = 10(0.2)^x

• y = 20(0.5)^x

• y = 10(0.5)^x

• y = 20(0.2)^x

What is the Y-intercept? A=______

What is the Ratio? B=_____

What is the Exponential Equation? f(x)=_____________

• A=2; B=4 $f\left(x\right)=2\cdot4^x$

• A=2; B=4 $f\left(x\right)=4\cdot2^x$

• A=2; B=4 $f\left(x\right)=8^x$

• A=2; B=6 $f\left(x\right)=2+6^x$

Benjamin has a savings account that his Nana created when he was born and let it sit for 30 years without any further deposits or withdrawals. What is a function that best represents the data?

16) Write the exponential regression equation for this set of data, rounding all values to two decimal places. Using this equation, find the value of her stock, to the nearest dollar, years after her initial purchase.

• $562

• $563

• $564

• $561

Sim City currently has 100,000 people and the population is decreasing 5.6%.

Which equations represent this scenario? Select all that apply.

• $y=100,000\left(1-5.6\right)^x$

• $y=100,000\left(1-0.56\right)^x$

• $y=100,000\left(1-0.056\right)^x$

• $y=100,000\left(0.944\right)^x$

• $f\left(t\right)=100,000\left(0.944\right)^t$

Write the equation for the following situation:
You buy a car for $26,500.  The car depreciates in value by 20% a year.  

• A = 26500(1+0.2)^t

  A = 26500(1.2)^t

• A = 26500(1+0.8)^t

  A = 26500(1.8)^t

• A = 26500(1-0.2)^t

  A = 26500(0.8)^t

• A = 26500(1-0.02)^t

  A = 26500(0.98)^t

Warren invested $50,000 into an off-shore savings account with an astounding annual interest rate of 6%. Write an equation to model the account balance over time, x, in years.

• y = 50000(1.06)^x

• y = 50000(6)^x

• y = 6(50000)^x

• y = 1.06(50000)^x

In the year 1900, the total number of metric tons of copper produced in the world was 495,000. Each year since 1900, the total number of metric tons of copper produced has increased on average by 3.25% over the amount produced the previous year.

Which function models the total number of metric tons of copper produced in the year that is x years since 1900?

The population of a town is currently 6342 and is increasing by a rate of 1.3% each year. Which function represents the population of people, P, after t years.

• P = 6342(1 + 1.3)^t

• P = 6342(1 – 1.3)^t

• P = 6342(1 + .013)^t

• P = 6342(1 – .013)^t