SOLUTION: Construct a 95% confidence interval for the mean age at which a baby first crawls. Select the correct choice and, if necessary, fill in the answer boxes to complete your choice.

Question 1076063: Construct a 95% confidence interval for the mean age at which a baby first crawls. Select the correct choice and, if necessary, fill in the answer boxes to complete your choice.
The numbers are: 52, 30, 44, 35, 47, 37, 56, 26, 52, 39, 44, 47
I know the mean is 42.42, standard deviation is 9.22, and normal probability plot correlation is 9.22. I just am having a hard time getting the right answer.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
The confidence interval for a sample is mean +/-t(df=11,0.975)s/sqrt(n); t=2.201
The interval is +/-2.201*9.22/sqrt(12)=5.86
The 95% CI is (36.6, 48.3)
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