Quarterly sum the values with interest rate

I am trying to make two columns.
* [SOLVED] A type Column is summing up past amount with a defined interest rate (e.g. 3%)
* B type Column is summing up future amount with a defined interest rate (e.g. 3%)

For an example,
AMOUNT QUARTER B Column
100 1Q 1566.389
150 1Q 1510.48
200 1Q 1401.192
250 2Q 1237.23
300 2Q 1016.84
350 2Q 738.35
400 3Q 400

However, I also want to show up only the last month of its quarter
Such as,
AMOUNT QUARTER B Column
100
150
200 1Q 1401.192
250
300
350 2Q 738.35
400 3Q 400

I have attached a full version of excel with two identical grouping criteria. I would be appreciated with your help!!!
Thanks,

For After-A. In J2 copied down

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For After-B how calculation is done . Pl show in file just like After-A.

In K2 then copy down

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