To solve this problem, we can break it down into two parts: first, we need to calculate the future value of Derek's deposits at the time they stop being deposited, and then we will find out how much that amount will grow over the remaining years until the specified time.
Step 1: Calculate the future value of the deposits
Derek deposits $4,735.00 per year for 10 years, starting 6 years from today.
1. Calculate the future value of an annuity:
The formula for the future value of an annuity is:
\[ FV = PMT \times \frac{(1 + r)^n - 1}{r} \]
Where:
- \( FV \) = Future Value of the annuity
- \( PMT \) = Payment per period ($4,735.00)
- \( r \) = Interest rate per period (10% or 0.10)
- \( n \) = Number of periods (10 years)
Substituting in the values:
\[ FV = 4735 \times \frac{(1 + 0.10)^{10} - 1}{0.10} \]
Calculating \((1 + 0.10)^{10}\):
\[ (1 + 0.10)^{10} \approx 2.5937 \]
Now, substituting back into the FV formula:
\[ FV = 4735 \times \frac{2.5937 - 1}{0.10} \approx 4735 \times \frac{1.5937}{0.10} \approx 4735 \times 15.937 \approx 75,389.55 \]
So, at the end of Year 15 (which is when the last deposit is made for 10 years starting 6 years from today), the future value of the annuity is approximately $75,389.55.
Step 2: Calculate the future value at the end of an additional 16 years
After the last deposit is made at the end of year 15, we need to find out how much this amount will grow over the next 16 years (from Year 15 to Year 31).
We will use the future value formula as:
\[ FV = PV \times (1 + r)^t \]
Where:
- \( FV \) = Future Value
- \( PV \) = Present Value ($75,389.55)
- \( r \) = Interest rate (0.10)
- \( t \) = Number of years (16)
Substituting in the values:
\[ FV = 75,389.55 \times (1 + 0.10)^{16} \]
Calculating \((1 + 0.10)^{16}\):
\[ (1 + 0.10)^{16} \approx 4.505 \]
Now substituting back into the FV formula:
\[ FV = 75,389.55 \times 4.505 \approx 339,375.45 \]
Final Answer
Therefore, the total amount that will be in the account 31 years from today is approximately:
\[ \boxed{339,375.45} \]