Susanna saves $40 at the end of each week and deposits the money in an account paying 9% compounded semi-annually. How much will Susanna accumulate in 6 years? How much of the accumulated amount is interest? (The correct answer to the first question is somewhere either $16,427.88 or $16,427.37 or $16,426.80, give or take 0.86 in any of those. The correct answer to the second question is either $3947.88 or $3947.37 or $3946.80, give or take 0.86 in any of those. How do we get to that answer?)