SOLUTION: In a study of brain waves during sleep, a sample of 29 college students were randomly separated into two groups. The first group had 15 people and each was given ½ litre of red wi

Question 1183970: In a study of brain waves during sleep, a sample of 29 college students were randomly separated into two groups. The first group had 15 people and each was given ½ litre of red wine before sleeping. The second group had 14 people and were given no alcohol before sleeping. All participants when to sleep at 11 PM and their brainwave activity was measured from 4-6 AM. The group drinking alcohol had a mean brainwave activity of 19.65 hertz and a standard deviation of 1.86 hertz. The group not drinking alcohol had a mean of 6.59 hertz and standard deviation of 1.91 hertz. Compute a 90% confidence interval for the difference in population means of groups drinking alcohol before sleeping and those not drinking alcohol before sleeping. Explain the meaning of the confidence interval. (10 points)
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
The half interval is t(0.95, df=27)* sqrt (s1^2/n1+s2^2/n2)
=1.703*sqrt((1.86^2/15)+(1.91^2/14))
=1.703*0.700
=1.19
The point estimate of the difference is 13.06 Hz
so the interval is (11.87 Hz, 14.25 Hz)
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