The formulae = A= P(1+ r/n) ^nt .......where P is the principal amount, r is the rate of interest in decimal, n is number of compoundings per year and t is the total number of years.
Given; P= $4,000.00 , r=12/100=0.12, n=2 and t=3
Substituting values in the equation A= P(1+ r/n) ^nt