Answer:
$91,749.04
Explanation:
Lets use the compound interest formula provided to solve this:

P = initial balance
r = interest rate (decimal)
n = number of times compounded annually
t = time
First, change 2.3% into a decimal:
2.3% ->
-> 0.023
Since the interest is compounded monthly, we will use 12 for n. Lets plug in the values now:


You will have $91,749.04 in 15 years.