Find the standard normal area under the curve for each of the following:
27. (2 points) P(–1.22 < Z < 2.15)
A. 0.1370
B. 0.5000
C. 0.8730
D. None of the above
28. (2 points) P(Z > 0.50)
A. 0.3085
B. 0.7015
C. 0.5000
D. None of the above
29. (2 points) P(Z < 1.96)
A. .0250
B. 0.9750
C. 0.1960
D. None of the above
30. (4 points). Find a confidence interval for μ assuming that the sample is from a normal population with
known population standard deviation.
x = 20, σ = 3, n = 100, 95 percent confidence
A. (20.412 , 21.588)
B. (18.214 , 21.885)
C. (19.412 , 20.588)
D. None of the above
31. (4 points). Find a confidence interval for μ assuming that the sample is from a normal population with
unknown population standard deviation.
x = 40, s = 9, n = 20, 95 percent confidence
A. (52.788 , 54.212)
B. (35.788 , 44.212)
C. (34.887 , 45.212)
D. None of the above
32. (4 points). Find a confidence interval for μ assuming that the sample is from a normal population with
unknown population standard deviation.
x = 20, s = 3, n = 10, 95 percent confidence
A. (17.854 , 22.146)
B. (19.854 , 22.146)
C. (16.854 , 23.146)
D. None of the above
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