A program evaluator for a large school district wants to know how much intelligence varies in the elementary schools. She selects one classroom at each grade level in each elementary school and administers an intelligence test to the children in those classrooms. If the program evaluator wants to find out which school has the highest intelligence level, which of the following should she calculate for each school?
a. The variance
b. The standard deviation
c. The sum of the deviations
d. The mean