SOLUTION: Suppose you are trying to estimate the average miles per gallon for a new brand of car. You take a random sample of 40 cars, and, for this sample, the average per gallon is 32 and

Question 1120539: Suppose you are trying to estimate the average miles per gallon for a new brand of car. You take a random sample of 40 cars, and, for this sample, the average per gallon is 32 and the standard deviation is 2.2.
1) Suppose you would like to construct a 90% confidence interval. What would the margin of error for this interval?
2) What would be the lower and upper limits for this 90% confidence interval?
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
This is a t confidence interval with s=2.2 mean 32 and n=40
t=+/-1.68
90%CI is t*s/sqrt(n)=+/-1.68*0.3479=0.584 margin of error
(31.416, 32.584) third decimal place depends upon where rounding occurs. I rounded at end.
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