Only the CF High students is a subset of the population, hence a sample. The populations of each state are parts of the total population of New England, hence can be represented by a pie chart. Neither the per capita income for each state nor the immigrant percentage of each state are parts of a whole for all of New England. Unfortunately, there are several definitions of quartiles. The variance would change by a factor of four, since its numerator is a sum of squared differences.
Most days have at or near full attendance, a few days have low attendance.
None of the numbers are in the 60's. You will include the stem 6 so that the visual presentation will not be confusing, but the stem 6 will not have any leaves. We want equal area under the histogram on both sides of the median. The area of the first rectangle is 100, hence 75 is needed from the second. The least possible mean is obtained when the data is as leftward as possible,consistent with the histogram.