The following stem-and-leaf plot represents the scores earned by mr. roberts's class on their most recent science test.

what is the median of the scores?
78
80
81
86

The median of {78, 80, 81, 86} is the average of the middle two scores, 80.5.


For the picture, ...

There are 7 scores above the row with stem=8, and 7 scores below that row. Thus the middle score will be the middle score of the row with stem 8.

The median of the scores in the figure is 81.

The vertex of the quadratic function is (1.5, -.75)