A = P(1 + r/n)^(nt)
Where:
A = the amount of money after t years
P = the principal amount (in this case, $4000)
r = the annual interest rate (as a decimal)
n = the number of times the interest is compounded per year (in this case, twice a year, so n = 2)
t = the number of years
Plugging in the given values, we get:
A = 4000(1 + 0.02/2)^(2t)
Simplifying, we get:
A = 4000(1.01)^2t
Therefore, the function that models the situation is:
A = 4000(1.01)^(2t)