Interest Payment on a growing annuity problem?

Hi, I'm currently doing a spreadsheet for my college course. We have to do an amortization table for a growing annuity. My Present Value is correct, as I used the sample table he gave us as a guide and mine matches his. My payments all line up as well. The only thing that is different is the interest payment. The first interest payment is correct, according to the sample table, but the second is low. It should be 880.45 but is 851.91. All the other payments are low as well and I end up with a negative number as my final value. I have literally tried everything to fix this issue but nothing has worked and I literally can't find anything online to help me with interest payments for growing annuity.


he formula I used to calculate interest payment is =ipmt($V$4,W7,$V$3,$X$7).


The rate ($w$4) is 15% and payments are done annually, so I don't have to change the rate. The period number (w7) changes as I go down the column, and my number of periods (v3) is correct too. And the present value I have is the correct one that he had. It does not make a difference whether I say it's done at the end of the period or the beginning. So yeah, I have no idea where I'm going wrong here. Could use some help, thanks.


Solution: All I did was multiply the interest rate by the previous amount and it worked.

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