The principals at 5 middle schools asked their teachers if they preferred a shorter work day or a shorter school year. Afterward, Mr. Howard asked the same question of some of the teachers at his school.

Of the 500 teachers in the principals’ survey, 220 said they preferred the shorter work day.
Of the 10 teachers in Mr. Howard’s survey, 4 said they preferred the shorter school year.
Which statement best explains why Mr. Howard’s results are different from the principals’ results?