What is the z-score of sample X, if #n = 100, mu= 45, SD =30, and E[X] =31#?

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Answer 1 · 2016-12-15T07:28:35

The z-score is #=-5#

The z-score for a sample mean is

#z=(barx-mu)/(sigma/sqrtn)#

#barx=E [X] =31#

#mu=45#

#sigma=30#

#n=100#

#z=(31-45)/(30/sqrt100)=(-15)/(3)=-5#