If Don Gecewicz invests $5000 at 9% interest compounded quarterly, find the amount after 4 years.

$104,924

To find the amount after 4 years, we can use the formula for compound interest:

A = P(1 + r/n)^(nt)

Where:
A = the amount after t years
P = principal amount (initial investment)
r = annual interest rate (as a decimal)
n = number of times that interest is compounded per year
t = number of years

In this case, Don Gecewicz invests $5000, the interest rate is 9% (or 0.09 as a decimal), and it is compounded quarterly, so n = 4. We need to calculate the amount after 4 years, so t = 4.

Using the formula, we can substitute the given values:

A = 5000(1 + 0.09/4)^(4*4)

Simplifying the equation:

A = 5000(1 + 0.0225)^(16)
A = 5000(1.0225)^(16)

Now, let's calculate it step by step:

A = 5000 * (1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225 * 1.0225)
A ≈ 5000 * 1.4318727
A ≈ $7,159.36

So, the amount after 4 years for Don Gecewicz's investment of $5000 at 9% interest compounded quarterly would be approximately $7,159.36.