Monica invested $$2,000$ at the beginning of every $6$ months in an RRSP for $11$ years. For the first $4$ years it earned interest at a rate of $4\mathrm{.}60\%$ compounded semi$-$annually and for the next $7$ years it earned interest at a rate of $6\mathrm{.}40\%$ compounded semiannually.

a$.$ Calculate the accumulated value of her investment after the first $4$ years.

Round to the nearest cent

b$.$ Calculate the accumulated value of her investment at the end of $11$ years.

Round to the nearest cent

c$.$ Calculate the amount of interest earned from the investment.

Round to the nearest cent