Question

Suppose you are told that a 95% confidence interval for the average price of a gallon of regular gasoline in your state is from $3.33 to $3.60. Use the fact that the confidence interval for the mean is in the form x − E to x + E to compute the sample mean and the maximal margin of error E

Answer 1

Sample mean is $3.465 and margin of error is 0.135

Explanation:

Given the confidence interval $3.33 to $3.60, we can conclude that

1. X-E=$3.33
2. X+E=$3.60 where

• X=sample mean
• E=margin of error

Adding the equations 1 and 2 we get

(X-E)+(X+E)=X+X= $3.33 + $3.60, from this we can find X=3.465 and E=0.135