Calc Help - Interest/Geometric Series?

Question

Anyone help me with this problem? I got an answe but my web based hw tells me it's wrong and I'm stumped..

Scott and Amanda want to purchase a house. Suppose they invest 400 dollars per month into a mutual fund. How much will they have for a downpayment after 8 years if the per annum rate of return of the mutual fund is assumed to be 9.5 percent compounded monthly?

Answer 1

So you're summing 400 * (1 + R) ^ j, where R is the monthly interest rate. (That is, R = .095/12).

Frankly, the wording of the problem is a little unclear. My best guess is that they put in the money at the beginning of the month for 96 consecutive months, and the question is what they got out at the end of the 96th month. In that case, the sum is taken as j goes from 1 to 96. But the problem could also be read to ask for the sum as j goes from 0 to 95.

If I had to turn that in, I'd explain how it could be read to be either of those figures, turn in both numbers (obviously, one of them is just (1+R) times the other one), and say which one I thought was more likely to have been meant.

Answer 2

a geometrical series has a series ratio between consecutive words. a capacity series does no longer. Restated, a geometrical series will be concept-about as particular case of a capacity series the position the whole series is prolonged by technique of a few consistent a and human being words have a coefficient of one million. Geometric: y = a? a million + x^2 + x^3 + x^4 + . . .x^n capacity: y = ? a + bx^2 + cx^3 + dx^4 + . . .?x^n, the position ? represents the nth coefficient.