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Chapter 6: Introduction to

(b) Last year, your company s service technicians took an average of 2.6 hours to respond to trouble calls from business customers whc had purchased service contracts. Do this year s data show a differe average response time?

6.35    A test of the nuli hypothesis Hq: /i Ęę /jlo gives test statistic z - 1.8.

(a)    What is the P-value if the ałtemative is    /i.o?

(b)    What is the P-value if the altemative is H_a\ jul < jjlq?

(c)    What is the P-value if the altemative is H_a\ /jl

6.36    The P-value for a two-sided test of the nuli hypothesis Ho: fi = 10 is 0.

(a)    Does the 95% confidence interval include the value 10? Why?

(b)    Does the 90% confidence interval include the value 10? Why?

6.37    A 95% confidence interval for a population mean is (28, 35).

(a) Can you reject the nuli hypothesis that fi = 34 at the 5% signfi| level? Why?