The formula for compound interest is: A=P(1+r/n)^(nt) Where A represents the amount of money in the account after t years, P is the principal (investment), n is the number of compoundings per year, and r is the interest rate in decimal form. P=11,100 r=.031 n=12 (monthly) t=19 A=11,100(1+.031/12)^(12*19) A=11,100(1+. 002583)^(228) A=11,100(1.002583)^(228) A=11,100(1.80082) A=$19,989.10