if the distribution is normal the median equals the average. What's really important in this case, besides the fact that Perry is healthy right now, is the shape of the distribution. If it's broad, then many beagles live a lot longer than the median, and that would be a good thing of course. But you can't use a population statistic to meaningfully predict the fate of an individual anyway. His current state of health is far more indicative. Another good thing.