Essentials of Statistics for Business and Economics
9th Edition
ISBN: 9780357118191
Author: David R. Anderson, Dennis J. Sweeney, Thomas A. Williams
Publisher: Cengage Learning US
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Chapter 11.1, Problem 10E
Costco Customer Satisfaction. Consumer Reports uses a 100-point customer satisfaction score to rate the nation’s major chain stores. Assume that from past experience with the satisfaction rating score, a population standard deviation of σ = 12 is expected. In 2012, Costco, with its 432 warehouses in 40 states, was the only chain store to earn an outstanding rating for overall quality. A sample of 15 Costco customer satisfaction scores follows.
- a. What is the sample
mean customer satisfaction score for Costco? - b. What is the sample variance?
- c. What is the sample standard deviation?
- d. Construct a hypothesis test to determine whether the population standard deviation of σ = 12 should be rejected for Costco. With a .05 level of significance, what is your conclusion?
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30. An individual who has automobile insurance from a certain company is randomly selected. Let Y be the num- ber of moving violations for which the individual was cited during the last 3 years. The pmf of Y isy | 1 2 4 8 16p(y) | .05 .10 .35 .40 .10
a.Compute E(Y).b. Suppose an individual with Y violations incurs a surcharge of $100Y^2. Calculate the expected amount of the surcharge.
24. An insurance company offers its policyholders a num- ber of different premium payment options. For a ran- domly selected policyholder, let X = the number of months between successive payments. The cdf of X is as follows:
F(x)=0.00 : x < 10.30 : 1≤x<30.40 : 3≤ x < 40.45 : 4≤ x <60.60 : 6≤ x < 121.00 : 12≤ x
a. What is the pmf of X?b. Using just the cdf, compute P(3≤ X ≤6) and P(4≤ X).
Chapter 11 Solutions
Essentials of Statistics for Business and Economics
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