SOLUTION: Your statistics tutor wants you to determine a confidence interval estimate for the mean score in next exam. In the past the scores have been distributed normally with a mean of 74

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Question 335287: Your statistics tutor wants you to determine a confidence interval estimate for the mean score in next exam. In the past the scores have been distributed normally with a mean of 74.2 and a standard deviation of 30.9. A 95% confidence interval if your class has 30 students is
1. (68.72;79.68)
2. (13.64;34.76)
3. (64.92;83.48)
4. (63.14;85.26)
5. (62.66;85.73)
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
First find the standard error of the mean,
s=sigma%2Fsqrt%28N%29=30.9%2Fsqrt%2830%29=5.642
.
.
(xave-1.96%2As,xave%2B1.96%2As)=(74.2-1.96%2A5.642,74.2%2B1.96%2A5.642)
.
.
(xave-1.96%2As,xave%2B1.96%2As)=(63.14,85.26)