Formula to return range based on criteria

Hi All

I am trying to figure out a formula that will return a range based on specific criteria. For example:

Criteria 1: Column A, Criteria 2: Column B. When both a fulfilled return A1:A15. I've attached a basic example, looking for a formula to return the range under the red column. Example 1.xlsx

Appreciate any help and thank you so much for your time and energy!

Edit: Using Microsoft® Excel® for Microsoft 365 MSO (Version 2302 Build 16.0.16130.20806) 64-bit if it matters

Edit 2: I updated the attachment with the exact details I am trying to work on, there is a new tab "Specific Example" which *crossed fingers* I have completely made generic. The focus is in rows 4 through 9, the "Median", "Fit range" and "Pop" columns. I have currently performed the range selections for each of them manually but I would like to automate the range selection in the median, countifs and count formula so that people can mess with the underlying population and the calculations update automatically

Thank you russkris for taking the time to respond. The specific reason I wanted a formula to return the range, was because I want to use the median formula on the range, and then calculate how many items fall within 20% of the median. I am currently populating the range in the median and countifs formula manually but wanted to automate the range calculation. I plan to hand the file over to someone who isnt proficient with excel and if they added rows in the population it would automatically update all the calculations.

Omg that's awesome, thank you. I should be able to replicate the filter formula for the range sections in the countifs formula as well right?

Edit: not sure why i keep getting an excel error "There is a problem with this formula. Not trying to type formula.....etc"

I've always experienced this when my brackets are generally wrong. Doesnt seem to be here. trying to replicate the filter formula in the countifs formula in cell F4 "=COUNTIFS(FILTER($C$12:$C$171,(A4=$A$12:$A$171)*(B4=$B$12:$B$171))},">="&D4,FILTER($C$12:$C$171,(A4=$A$12:$A$171)*(B4=$B$12:$B$171)),"<="&E4)"