In a group of 68 students, each student is registered for at least one of three classes - History, Math and English. Twenty-five students are registered for History, twenty-five students are registered for Math, and thirty-four students are registered for English. If only three students are registered for all three classes, how many students are registered for exactly two classes? A. 13B. 10C. 9D. 8E. 7

c. 10

Explanation:

We have 68 students, 3 of them are registered in three classes, so (68-3 = 65), 65 students are registered in one or two classes.

Additionally, we know that:

25 students are registered for History. 25 students are registered for Math 34 students are registered for English

If we want to know only the registrations of students that are registered for one or two classes, we should substract 3 in every class (the three students that ar registered for the three classes)

So, now we have:

22 students registered for History. 22 students registered for Math 31 students registered for English

Total registrations for stdents registered in one or two clases: 22+22+31 = 75

75 registrations of 65 students

So 75-65=10 ... There are 10 students registered for 2 classes.