1. A Type I error in a test of hypothesis occurs (a) if we do not reject H0 when
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Question
1. A Type I error in a test of hypothesis occurs
(a) if we do not reject H0 when H0 is really true
(b) if we do not reject H0 when Ha is really true
(c) if we reject H0 when Ha is really true
(d) if we reject H0 when H0 is really true
(e) if we do not reject H0 when H0 is really false
2. In the test of hypotheses H0 :µ = ?28 Vs Ha :µ ? ?28 at the 1% level of significance, when the sample size is 40 and ? is unknown, the rejection region will be the interval or union of intervals:
(a) [2.426,?)
(b) (-?,-2.708]U[2.708,?)
(c) (-?, -2.426]
(d) (-?, -2.575]U[2.575, ?)
(e) (-?, -2.326]U[2.326, ?)
3) An automobile manufacturer recommends oil change of 3,000 miles. To compare actual intervals to the recommendation, the company randomly samples records of 50 oil changes at service facilities and obtains sample mean 3,752 miles with sample standard deviation 638 miles. Determine whether the data provide sufficient evidence, at the 5% level of significance, that the population mean interval between oil changes exceeds 3,000 miles.
(a) reject the null hypothesis
(b) fail to reject the null hypothesis
4)For the past few years the average score on a common final exam in Psychology has been 80. In a sample of 92 students, the mean score on this year’s exam was 82 with standard deviation 8.7. Test at 5% level of significance whether the mean score this year’s exam is higher than that of previous years.
(a) Reject the null hypothesis
(b) Fail to reject the null hypothesis
Explanation / Answer
1 ) (d) if we reject H0 when H0 is really true.
2) (b) (-?,-2.708]U[2.708,?)
3) T= (X?-u)*sqrt(n)/s=8.334550
P-value= 2.95502E-11
rounded p-value=0.0000
Decision making
P-value ? Alpha Reject H0
0.0000 < 0.05
reject null hypothesis
(a) reject the null hypothesis
4)
Test Statictics
T= (X?-u)*sqrt(n)/s=2.2049800
P-value=0.014988038
rounded p-value=0.015
Decision making
P-value ? Alpha Reject H0
0.015 <0.05
(a) reject the null hypothesis
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