# Fastest algorithm for extracting 25% and 75% marks

I'm hand rolling some visualization algorithms.

Extracting the min/max of a time series is $O(n)$, for n entries.

If I want the 25% and 75% mark, I could use an $O(n \log n)$ time sort, then get the 25% and 75% marks.

However, is there a way to do this in linear time?