A courier service advertises that its average delivery time is less than 6 hours for local deliveries. A comsumer advocate thinks otherwise. A random sample of times for 12 deliveries to an address across town was recorded. These data are shown below. Test to determine whether there is enough evidence to support the consumer group's beliefs, at the 0.25% significance level. 6.75 5.75 9 4.75 6.5 8.25 8.25 5.25 6.75 8.5 7.75 7.5 It is known that Ex = 85 and Ex = 622.25 for this sample.

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A courier service advertises that its average delivery time is less than 6 hours for local deliveries. A comsumer advocate thinks otherwise. A random sample of times for 12 deliveries to an address across town was recorded. These data are shown below. Test to determine whether
there is enough evidence to support the consumer group's beliefs, at the 0.25% significance level.
6.75 5.75
9.
4.75
6.5
8.25
8.25
5.25
6.75
8.5 7.75 7.5
It is known that x = 85 and x = 622.25 for this sample.
(a) The value of the standardized test statistic:
Note: For the next part, your answer should use interval notation. An answer of the form (-0o, a) is expressed (-infty, a), an answer of the form (b, co) is expressed (b, infty), and an answer of the form (-o, a) U (b, o0) is expressed (-infty, a)U(b, infty).
(b) The rejection region for the standardized test statistic:
(c) Your decision for the hypothesis test:
O A. Do Not Reject H1.
O B. Do Not Reject Ho.
O C. Reject H1.
O D. Reject Ho.
Transcribed Image Text:A courier service advertises that its average delivery time is less than 6 hours for local deliveries. A comsumer advocate thinks otherwise. A random sample of times for 12 deliveries to an address across town was recorded. These data are shown below. Test to determine whether there is enough evidence to support the consumer group's beliefs, at the 0.25% significance level. 6.75 5.75 9. 4.75 6.5 8.25 8.25 5.25 6.75 8.5 7.75 7.5 It is known that x = 85 and x = 622.25 for this sample. (a) The value of the standardized test statistic: Note: For the next part, your answer should use interval notation. An answer of the form (-0o, a) is expressed (-infty, a), an answer of the form (b, co) is expressed (b, infty), and an answer of the form (-o, a) U (b, o0) is expressed (-infty, a)U(b, infty). (b) The rejection region for the standardized test statistic: (c) Your decision for the hypothesis test: O A. Do Not Reject H1. O B. Do Not Reject Ho. O C. Reject H1. O D. Reject Ho.
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