We let x be the initial amount of money and r be the rate of interest (already in decimal) such that the equation for the future worth of money is,
after two years, F = 44100 = x(1 + r)^2
after four years, F = 48620.25 = x(1 + r)^4
Solving for the values of x and r in the equation will give us answers of 40,000 and 0.05, respectively. Thus, the interest rate is approximately 5%.
