A music streaming service is testing the impact of two different recommendation algorithms $($Algorithm PopFlow and Algorithm BeatSync$)$ on user engagement. In a trial, $100$ users were randomly assigned to experience recommendations generated by either PopFlow or BeatSync for a month. The results showed that users exposed to PopFlow had a mean increase in daily listening time of M $=30$ minutes $($s $=10$ minutes$),$ while those exposed to BeatSync had a mean increase of M $=25$ minutes $($s $=8$ minutes$).$ Calculate pooled variance.