A person pays $2000 into an investment fund every six months, and it earns interest at a rate of 6% pa, compounded monthly. How much is the fund worth at the end of ten years?
Answer: $55 586.38
Use the formula
$\displaystyle A = P(1 + r)^n$.
If the rate is $\displaystyle 6\%$ per year, then every month the rate is $\displaystyle \frac{6}{12}\% = 0.5\%$.
If it is being compounded monthly for $\displaystyle 10$ years, then there are $\displaystyle 120$ time periods.
That's NOT the correct formula; here:
Future value of an annuity - Google Search=
And n = 20, NOT 120
r = .03037... is correct