According to an automobile association, the average cost of a gallon ot regular

Question

According to an automobile association, the average cost of a gallon ot regular unleaded fuel at gas stations in a certain month was 2.828. Assume that the standard deviation of such costs is $0.15. Suppose that a random sample of n 100 gas stations is selected from the population and the month's cost per gallon of regular deviation of such costs is $0.15. Suppose that a random sample of n = 100 gas stations is selected from the population and the month's cost per gallon of regular unleaded fuel is determined for each. Consider x, the sample mean cost per gallon. Complete part a through d. Click the icon to view the table of normal curve areas. a. calculate . ana - = 2.828 (Do not include the $ symbol in your answer. Round to three decimal places as needed.) o-= 0.015 (Do not include the $ symbol in your answer. Round to three decimal places as needed.) b. What is the approximate probability that the sample has a mean fuel cost between $2.84 and $2.86? P(2.84% x 2.86) = Round to four decimal places as needed.)

Explanation / Answer

b) distribution of sample mean with mean 2.828 and standard deviation = 0.015

P(2.84<=x<=2.86) = P(0.8<=z<=2.133) = 0.9836-0.7881=0.1954

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