10% of students in a university are dissatisfied with the services at their cafe. 10 students were selected randomly and were asked to fill out surveys.
(a) In this group of 10 students, what is the mean and variance of the number that were dissatisfied?
(b) If, instead, 55% of the students were dissatisfied, what is the probability that at least half of the 10 would be dissatisfied?
(c) If 55% of the students were dissatisfied and 200 were selected randomly, what is the probability that at least half would be dissatisfied? Can this problem be done using the Normal Distribution? Why? If yes, solve it using the Normal Distribution.