To find the median, first list the daily kilowatt-hours in order:
19, 24, 27, 29, 31
The median = 27
To find the average, we could add up all the terms and divide by 5. Instead, though, just see how much each term differs from the median:
19 --> 27 - 8
24 --> 27 - 3
27
29 --> 27 + 2
31 --> 27 +4
-8 + -3 + 2 + 4 = -5 overall
In other words, the overall sum is 5 less than the sum of the hypothetical set 27, 27, 27, 27, 27.
Therefore, the average must be 1 less than the sum of the hypothetical set 27, 27, 27, 27, 27.
--> -5 divided across 5 terms.
Thus, the median is 1 greater than the mean.
The answer is A.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
