According to the American Automobile Association, the average cost of a gallon of regular unleaded fuel at gas stations in January 2019 was $3.5. Assume that the standard deviation of such costs was $4.75. Suppose that a random sample of 56 gas stations was selected from the population and the cost per gallon of regular unleaded fuel was determined for each gas station. Consider X¯bar, the sample mean cost per gallon. (a) Describe the sampling distribution of X¯bar. (b)Find the probability that the sample had a mean fuel cost between $3.8 and $4. (c) How would the sampling distribution of X¯bar change if the sample size were doubled?

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A: mean = 760 s = 120 n = 1000

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A: Here  Standard deviation of sample mean = σn

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A: The standard deviation of the distribution of sample means would be equal to ?

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Q: A recent study of 1,215 randomly selected middle school students revealed that the average number of…

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Estimation

A new framework of data analysis where the new statistical methods are used for interpreting the results and analyzing the data is known as estimation in statistics.