Question 358146: A special investigation is conducted to study the blood pressure of people with glaucoma. In the study, 21 people with glaucoma are recruited with a mean systolic blood pressure of 140 mm Hg and a standard deviation of 25 mm Hg. Construct a 95% confidence interval for the mean systolic blood pressure among people with glaucoma.
Since the work I did is so extensive I'll just tell you what I got...
the formula I used, with the numbers plugged in, was:
140 + or - (1.725)(25/sqrt(21)) and I got the interval of 130.59, 149.41...If this is correct please let me know!
THANK YOU!!
Answer by jrfrunner(365)   (Show Source):
You can put this solution on YOUR website! your answer is almost correct
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your critical value is not correct.
The proper t critical value should be 2.0859 which represent a two tail t critical value with 20 dof and 5% tail probability (or 95% confidence)
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Your critical value would be fine for 20 dof and 10% tail probability or 90% confidence.
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otherwise, your answer is correct
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