The following is the statistical table of the number of extracurricular interest groups in experimental primary schools. Number of people (persons) in the Olympic Games of Dance, Calligraphy and Art:

Therefore, the Austrian Front has the largest number of people, 28; The calligraphy group has the least number of people,12;

(2)20+ 12+24=56 (person);

A: Excluding the Olympic array, there are 56 people in three groups.

(3)(20+ 12+24+28)÷4

=84÷4

=2 1 (person)

A: On average, each group is 2 1 person.

So the answer is: olympiad, 28, calligraphy, 12, 56, 2 1.