The formula for compound interest is:
A = P(1 + r/n)^nt
where:
A is the total amount of money after t years,
P is the initial principal or deposit amount (in this case $1000),
r is the annual interest rate as a decimal (in this case 1.3% or 0.013),
n is the number of times interest is compounded per year (in this case, let's assume it's compounded annually), and
t is the number of years.
So, the function modeling the total amount of money Brigitte has over time, t, would be:
A = $1000(1 + 0.013)^t
This function shows how the amount of money in the savings account will increase as time goes on due to compound interest.