Formula to count a data point in the last nth number of observations in a column

Good Afternoon All,

This is my issue:

I have a workbook containing two columns of data to which I add rows of data every day. I currently employ a formula to count the last nth (last 5, last 10, last 15 etc) number of observations in the column:

=SUM(INDEX(L90:L324,MATCH(9.99999999999999E+307,L90:L324,1)):INDEX(L90:L324,MATCH(9.99999999999999E+307,L90:L324,1)-9,0))

This formula will sum the values of the last 10 observations in my dataset (COLUMN B below, total observations in column B is over 1000). What I want to now do is only sum the last nth values in Column B which meet a specific criteria. So for example, in the extract below, I want excel to count the last 3 observations in column B where the criteria is met in column A. So lets say the criteria is 1.75, I would want excel to count the last 3 observations in column B where column A = 1.75 - I would expect a total of 3 + 7 + 3 = 13. I have tried variou sumifs but to no avail

A B
1.65 4
1.4 5
1.6 4
1.75 3
1.65 4
1.6 6
1.85 7
1.75 3
1.75 7
1.85 4

Thanks for reading my post and any help would be appreciated.

RS

Hello RS, try this...

=SUMPRODUCT((A2:A10=1.75)*(ROW(A2:A10)>=LARGE((A2:A10=1.75)*ROW(A2:A10),3)),B2:B10)

Adjust the ranges.

If range doesn't have at least three 1.75 values in A2:A10, will give an error.