## Elementary Statistics (12th Edition)

The mean can be counted by summing all the data and dividing it by the number of data: $\frac{-15-18-32-21-9-32+11+2}{8}=-14.25$, the mean is -14.25. The mode is the data occuring the most times, which here is -32 appearing twice. The median is the average of the 1 or 2 (here 2) middle data: (-15-18)/2=-16.5, the median is -12. The midrange is the average of the highest and the lowest data: (-32+11)/2=-10.5, the midrange is -10.5. American Airlines' performance is really good because most of their flights seem to arrive early.