Distribution of 15 apartments; one apartment had a higher rent, and outlier caused the mean rent to be higher than the median rent. does this make sense?

Yes because the mean is the calculated average and would be increased by the outlier. The median is just the rent that is in the middle when you line all the rents up from highest to lowest. So the median would be the same regardless of what the highest rent was

The answer is 109 times per second