Practice Exam

Abstract

Problem 1: The following data are from a study conducted to study the customer satisfaction levels for an overnight shipping business. In addition to the customer's satisfaction level, the customers were asked how often they used overnight shipping. The results are summarized in the following table: Satisfaction Level Frequency of Use High Medium Low TOTAL < 2 per month 250 140 10 400 2-5 per month 140 55 5 200 > 5 per month 70 25 5 100 TOTAL 460 220 20 700 Assume that one customer is chosen at random and answer the following questions. Show your work. a) What is the probability of the customer being highly satisfied? b) What is the probability that they would use the company more than five times per month and have low satisfaction? c) Given that the customer uses the company at least two times per month, what is the probability that they are highly satisfied with the company? Problem 2: A discrete random variable x can assume five possible values: 0, 1, 2, 3, 4. The probability distribution for x is shown below. x 0 1 2 3 4 p(x) .3 .1 ? .1 .2 a) What is P(x=2)? b) Calculate the mean and standard deviation for x.