% Mistakes with simple data

[Sordini]

Here is what I need, a fixed sereis of cells to draw a dashboard from. The requirements on the fixed cells are:
- Last 10 data points.
- % of which have mistakes.

in the example above the answer is 90%, however as the database grows how would you write formula to keep refering to the most recent entries?

[teylyn]

start in a cell in row 11 and copy down. Format result as %

=COUNTIF(C2:C11,"Y")/COUNTA(C2:C11)

or, in any cell just looking at the last 10 occupied rows of the data table

=COUNTIF(INDEX(C:C,MATCH("zzz",C:C,1)-9):INDEX(C:C,MATCH("zzz",C:C,1)),"Y")/COUNTA(INDEX(C:C,MATCH("zzz",C:C,1)-9):INDEX(C:C,MATCH("zzz",C:C,1)))

[zbor]

This maybe:

=COUNTIFS(D:D, ">="&LARGE(D:D, 10), C:C, "Y")/COUNTIF(D:D, ">="&LARGE(D:D, 10))

[Sordini]

Dear god

That latter formula is amazing. Thank you very much!

[Sordini]

Thank you also zbor. That "large" function i never heard of and I will put that to good use in the future.

[Sordini]

new requirement from the boss.
large and small are great formula, it can be used for the top 5 smallest or larges data points. How about data points 6 - 10, 11 - 15? you see where I am going?

Many thanks