What is the z-score of sample X, if #n = 81, mu= 43, St. Dev. =90, and E[X] =57#?

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Answer 1 · 2016-11-21T08:06:25

The z-score is #=1.4#

The z-score for a sample mean is

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

#barx=E [X]=57#

#mu=43#

#sigma=90#

#n=81#

Therefore, #z=(57-43)/(90/sqrt81)#

#=14/(90/9)=14/10=1.4#