This test covers Algebra 2 exponential models: growth and decay with percent rates, compound interest with the number e, half-life, doubling time, and solving with logarithms (F-IF.C.8b, F-LE.A.4, F-LE.B.5). Eight questions are worth 20 points in total. A scientific calculator is allowed.
- Grade: Algebra 2
- Chapter: Exponential Functions and the Number e
- Common Core: F-IF.C.8b, F-LE.A.4, F-LE.B.5
- Time: 45 minutes
- Total: 20 points (Question 1: 2 pts; Question 2: 2 pts; Question 3: 2 pts; Question 4: 3 pts; Question 5: 3 pts; Question 6: 2 pts; Question 7: 3 pts; Question 8: 3 pts)
Question 1: Growth model (2 points)
The population of a city is modeled by \(P(t)=18000(1.045)^{t}\), where \(t\) is in years.
- State the initial population and the yearly percent growth. (1 point)
- Find the population after 8 years, to the nearest whole number. (1 point)
Question 2: Compound interest (2 points)
Jamal invests $2,400 at 3.2% interest compounded monthly for 5 years.
- Write the balance formula. (1 point)
- Find the balance to the nearest cent. (1 point)
Question 3: Continuous versus yearly (2 points)
Mei invests $1,800 at 4.5% for 12 years.
- Find the balance with continuous compounding. (1 point)
- Find the balance with yearly compounding and how much less it is. (1 point)
Question 4: Model from a graph (3 points)
The graph of \(f(x)=a\cdot b^{x}\) is shown.
- Find \(a\) and \(b\). (1 point)
- Write the equation. (1 point)
- Find \(f(4)\). (1 point)
Question 5: Solve for time (3 points)
An account follows \(A(t)=2000(1.04)^{t}\) dollars after \(t\) years.
- Solve \(2000(1.04)^{t}=3500\) exactly. (1 point)
- Give the solution to the nearest hundredth. (1 point)
- After how many full years does the balance first exceed $3,500? Justify. (1 point)
Question 6: Doubling time (2 points)
An investment grows by 6% each year. Find its doubling time to the nearest hundredth of a year.
Question 7: Half-life (3 points)
The graph shows the mass of a radioactive sample.
- Read the half-life from the graph. (1 point)
- Write a model for the mass \(A(t)\) after \(t\) days. (1 point)
- Find the mass after 12 days, to the nearest tenth of a mg. (1 point)
Question 8: Equivalent forms (3 points)
A quantity follows \(f(t)=500(1.12)^{t}\) with \(t\) in years.
- State the yearly percent growth rate. (1 point)
- Write an equivalent form \(500e^{kt}\) and give \(k\) to four decimal places. (1 point)
- Find the equivalent monthly growth rate as a percent, to the nearest hundredth. (1 point)
See every chapter on the Algebra 2 math page.



