A supervisor say average salary employee in his dept. 40,000 with a standard deviation 15,000. Sample of 25 employee salary was selected at random. what is probability avg. between 36,000 & 42,000

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Jessica -It looks like your class is working on sampling distributions using the Normal model.  The first two values in the problem (40,000 and 15,000) represent the population parameters for mean and standard deviation:μ=40000σ=15000The second part of the problem tells you that the sample size = 25.  The sample has the following statistics:SD = 15000/√(25) = 3000Now, let's assume these statistics follow a Normal distribution model.  If that is true, we determine what the probability is that the average is between 36000 and 42000 as follows:Pr(36000 ≤X≤ 42000)Pr[]Pr[-1.333≤ z ≤ 0.667]I'll leave it for you to look up this range of z-scores in your Normal table and determine the probability.Hope that helps