I have two worksheets in a workbook - say "Calculation" and "Ppl List". In
the "Calculation" sheet, I need to dynamically calculate percentiles for data
given in "Ppl List".

The "Ppl List" sheet has data for people's ages for different groups of
people, say groups A, B and C. The list is sorted based on Group, i.e. Group
A comes first, then Group B below that and so on. However, the number of
people in these Groups may change dynamically as and when names are removed /
added into the table. Therefore, in the Percentile formula, I cannot keep a
constant reference to an array of cells referring to the age for people in a
particular group as this would be subject to change.

How can I calculate the percentiles dynamically?