We could add another column to our figure above. This column would square each of the deviations and could be labeled x square. It is 40 in above when we add the sum of the squared deviations from 6. The exact midpoint of any distribution. Can be computed for ordinal, interval, and ratio data.
Every distribution has a median.
May or may not be actually earned by a student. Mo. That datum value that occurs most frequently. May have more than 1 mode - bimodal dist. But not always best. We would find these incomes do NOT make a normal distribution.