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 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 Cosco customer satisfaction scores follows.
95 90 83 75 95 98 80 83 82 93 86 80 94 64 62
a. What is the sample mean customer satisfaction score for Costco?
b. What is the sample variance?
c. What is the sample standard deviation?
Construct a hypothesis test to determine whether the population standard deviation of should be rejected for Costco. With a.05 level of significance, what is your conclusion?
1.) You plan to use an ANOVA to test the impact of drinks with different caffeine contents on students' test-taking abilities. What is the null hypothesis?
(a) The population mean test score for the cola population is different from the population mean test score for the black tea population.
(b) The population mean test scores for all three treatments are equal.
(c) The population mean test scores for all three treatments are different.
(d) The population mean test scores for all three treatments are not all equal.
2.) Calculate the degrees of freedom and the variances for the following ANOVA table:
Source
SS
df
MS
Between
-
-
-
Within
702.28
-
-
Total
973.14
-
The formula for the F-ratio is:
3.) Using words, the formula of the F-ratio can be written as:
4.) Using the data from the ANOVA table given, the F-ratio can be written as:
5.) Calculate for F-ratio:
6.) At the level of significance, what is your conclusion?
(a)You can reject the null hypothesis; you do not have enough evidence to say that caffeine affects test performance.
(b)You cannot reject the null hypothesis; caffeine does appear to affect test performance.
(c)You cannot reject the null hypothesis; you do not have enough evidence to say that caffeine affects test performance.
(d)You can reject the null hypothesis; caffeine does appear to affect test performance.
