To solve this problem, we need to use the future value of an annuity formula, which is given by:

$FV = P \times \frac{(1 + r)^n - 1}{r}$

Where:

• $FV$ is the future value of the annuity.
• $P$ is the annual payment (in this case, $20,000).
• $r$ is the annual interest rate (as a decimal, so 5.5% becomes 0.055).
• $n$ is the number of payments (in this case, 15 years).

Let's calculate it:

$FV = 20000 \times \frac{(1 + 0.055)^{15} - 1}{0.055}$

First, calculate $(1 + 0.055)^{15}$:

$(1 + 0.055)^{15} = 1.055^{15}$

Next, subtract 1 and divide by 0.055:

$\frac{(1.055)^{15} - 1}{0.055}$

Finally, multiply by the annual payment:

$FV = 20000 \times \left(\frac{(1.055)^{15} - 1}{0.055}\right)$

I'll calculate this step-by-step.The amount in the fund at the end of 15 years is approximately $448,173.27.

Do you want further details or have any questions? Here are five related questions that might interest you:

1. How would the future value change if the interest rate were 6% instead of 5.5%?
2. What would be the future value if the contributions were made monthly instead of annually?
3. How much interest is earned over the 15 years?
4. If the foundation decided to stop contributing after 10 years, what would the fund amount to at the end of 15 years?
5. How would the future value change if the annual contribution were increased to $25,000?

Tip: When dealing with annuities, always ensure the interest rate and payment frequency are consistent (e.g., annual payments with an annual interest rate).