Mind On Statistics - Chapter 13 Worksheets With Answers Page 14
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32Chapter 13
69. For a significance level of
= 0.05, are the results statistically significant?
A. No, results are not statistically significant because the p-value < 0.05.
B. Yes, results are statistically significant because the p-value < 0.05.
C. No, results are not statistically significant because the p-value > 0.05
D. Yes, results are statistically significant because the p-value > 0.05.
KEY: B
70. Which of the following is an appropriate conclusion?
A. The average delay for Airline 1 does appear to be less than the average delay for Airline 2.
B. The results are not statistically significant so there is not enough evidence to conclude the average delay for
Airline 1 is less than the average delay for Airline 2.
C. The average delay for Airline 1 is at least 3 minutes less than Airline 2.
D. None of the above.
KEY: A
Questions 71 to 75: A bank official wants to assess if the average delays for two airlines are different.
Let
= average delay for Airline 1 and
= average delay for Airline 2. A random sample of 10 flights for
1
2
Airline 1 shows an average of 6 minutes delay with a standard deviation of 5 minutes. A random sample of 10
flights for Airline 2 shows an average of 12 minutes delay with a standard deviation of 5 minutes. Assume delay
times are normally distributed, but do not assume the population variances are equal. Use the conservative “by
hand” estimate for the degrees of freedom.
71. What are the appropriate null and alternative hypotheses?
0
A. H
:
= 0 and H
:
0
1
2
a
1
2
0 and H
B. H
:
:
= 0
0
1
2
a
1
2
C. H
:
= 0 and H
:
< 0
0
1
2
a
1
2
D. H
:
= 0 and H
:
> 0
0
1
2
a
1
2
KEY: A
72. What is the value of the test statistic?
A. t = 2.68
B. t = 1.50
C. t = 1.50
D. t = 2.68
KEY: A
73. For a significance level of 0.05, what is the critical value?
A. The critical value = 1.83.
B. The critical value = 2.10.
C. The critical value = 2.26.
D. None of the above.
KEY: C
74. Are the results statistically significant?
A. No, results are not statistically significant because | t | < 1.83.
B. Yes, results are statistically significant because | t | > 2.26.
C. No, results are not statistically significant because | t | > 2.26.
D. None of the above.
KEY: B
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