Suppose you are told that a 95% confidence interval for the average price of a gallon of regular gasoline in your state is from $3.36 to $3.82. 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. (Round your answers to two decimal places.)

Respuesta :

Answer: The sample mean = $3.59 and the margin of error is 0.23.

Step-by-step explanation:

The confidence interval for mean is given by :-

[tex]\overline{x}\pm\ E[/tex], where  [tex]\overline{x}[/tex] is the sample mean and E is the margin of error .

Given :  A 95% confidence interval for the average price of a gallon of regular gasoline in your state is from $3.36 to $3.82.

Lower limit of confidence interval : [tex]\overline{x}-\ E=3.36[/tex]     (1)

Upper limit of confidence interval : [tex]\overline{x}+\ E=3.82[/tex]     (2)

Adding (1) and (2) , we get

[tex]2\overline{x}=7.18\\\\\Rightarrow\ \overline{x}=3.59[/tex]

From (1) , we have

[tex]3.59-E=3.36\\\\\Rightarrow\ E=3.59-3.36=0.23[/tex]

Hence, the sample mean = $3.59 and the margin of error is 0.23.

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