A quarter of the students in the class are non-swimmers. Half of the non-swimmers signed up for the swimming course. Four non-swimmers did not sign up for the course. How many students in the class can swim and how many students are there in total in the class?
Four non-swimmers, who did not sign up for the course, make up half of the non-swimmers, i.e., there are a total of 8 non-swimmers. Non-swimmers represent a quarter of the students in the class, i.e., there are 24 swimmers (three times the number of non-swimmers) in the class. In total, there are 32 children in the class.

[ determination of the number of non-swimmers - 2 points, total number of students - 4 points]