# Determining 95% Confidence Interval and Mean

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Julie is an industrial psychologist. She is currently studying stress among executives of health corporations. She developed a survey that he believes measures stress. A score of 80 indicates dangerous stress. A random sample of 15 executives revealed the following stress scores.

Score

94

78

83

90

78

99

97

90

97

98

93

91

100

75

84

1. What is the 95% confidence interval for the population mean?

A. Upper is 85.2; lower is 94.4

B. Upper is 84.99; lower is 93.94

C. The confidence interval should not be calculated because the sample is too small.

D. There is not enough information to calculate a confidence interval.

E. The confidence interval is something else

2. Is it reasonable to conclude that the hospital executives have a mean stress level in the dangerous level?

A. Yes

B. No.

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##### Solution Summary

This solution assists with determining the 95% confidence interval for the population mean, and finds the mean.

##### Solution Preview

Mean for this data = 89.8

Standard deviation = 8.308

upper limit for 95% confidence interval

= 89.8 + 2.145*8.308/sqrt(15) = 94.4

upper limit for 95% confidence interval

= 89.8 - 2.145*8.308/sqrt(15) = ...

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