.0134 > .01 . do not reject null hypothesis at a=.05, reject and state that the Midwest is lower .0134 < .05 reject null hypothesis 2. CCN and ActMedia provided a television channel targeted to individuals waiting in supermarket checkout lines. The channel showed news, short features, and advertisements. The length of the program was based on the assumption that the population mean time a shopper stands in a supermarket checkout line is 8 minutes. A sample of actual waiting times will be used to test this assumption and determine whether actual mean waiting time differs from this standard. a. Formulate the null and alternative hypotheses. Since we are looking at difference Ho: μ = 8 Ha: μ ≠ 8 b. A sample of 120 shoppers showed a sample mean waiting time of 8.4 minutes. If σ = 3, what is the test statistic? T= 1.46 c. What is the critical value(s) for a level of significance of .05 and what is the rejection rule?
Critical Z at .05 = 1.96 so reject if the t value is greater or less than 1.96 1.46 < 1.96 REJECT d. Are waiting times different from the standard of 8 minutes? e. No, there is not sufficient evidence that waiting times are different that 8 minutes. f. Compute a 95% confidence interval for the population mean. Does it support your conclusion? Using x-bar=8.4 and sx=3 and n=120 7.86 to 8.94 (95% confident that waiting times are between 7.86 and 8.94 minutes.) Yes, this supports the conclusion that waiting times are 8 minutes because 8 is in the confidence interval.
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