Solve the problem.
-Use your graphing calculator to find how long it will take for $8000 invested at 4.8% per year compounded daily to triple in value. Find the answer to the nearest year. Use 365 days for a year.
A) 0 yr
B) 23 yr
C) 3,049,422 yr
D) 30,692 yr

Question

Quizplus · Accepted Answer

To find how long it will take for an investment to triple in value, we use the formula for compound interest: $A = P(1 + \frac{r}{n})^{nt}$, where $A$ is the amount of money accumulated after n years, including interest, $P$ is the principal amount (the initial amount of money), $r$ is the annual interest rate (decimal), $n$ is the number of times that interest is compounded per year, and $t$ is the time the money is invested for in years. Here, we want $A = 3P = 3 \times 8000$, $r = 0.048$, and $n = 365$. Solving for $t$ gives us the time in years. Using a graphing calculator to solve for $t$ gives us approximately 23 years.

Solve the Problem. -Use Your Graphing Calculator to Find How Long It Will