Suppose that in a class of 50 studetns the intstructor calls

Suppose that in a class of 50 studetns, the intstructor calls on students to answer questions, for each question selecting one student at random and without consideration of whom he has called on in the past. If the instructor asks 20 questions of the class, what is the expected number of students he would have called on?

Solution

the expected number =n*p

=20*(1/50) =0.4