Do you have a picture of the problem
The formula for calculating compound interest with yearly contributions is:
Balance = X*(1 + Y)^n + Z((1 + Y)^(n + 1) - (1 + Y)/Y)
where the balance is the money earned after n years invested
Y is the interest rate as a fraction
Z is the yearly contribution
X is the starting investment
Therefore the calculation for this example is:
Balance = 1200*(1 + 0.05)^48 + 1200((1.05)^49 - (1.05)/05)
= $249,393.5
Triangle b is larger than triangle a
