You asked all the students in a school “How many students are in your classroom?” 40 students answered 40, 40 students answered 20, and 20 students answered 10.

You asked all the students in a school “How many students are in your classroom?” 40 students answered 40, 40 students answered 20, and 20 students answered 10. What is the average classroom size in that school if each student only belongs to one class?
a) 20
b) 23
c) 28
d) 30
e) 33
f) None of the above