What is the z-score of sample X, if $n = 81, μ = 43, S t . D e v . = 90, and E [X] = 57$ $n = 81, mu= 43, St. Dev. =90, and E[X] =57$ ?

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Answer 1 · 2016-11-21T08:06:25

The z-score is $= 1.4$ $=1.4$

The z-score for a sample mean is

$z = \frac{¯ x - μ}{\frac{σ}{\sqrt{n}}}$ $z=(barx-mu)/(sigma/sqrtn)$

$¯ x = E [X] = 57$ $barx=E [X]=57$

$μ = 43$ $mu=43$

$σ = 90$ $sigma=90$

$n = 81$ $n=81$

Therefore, $z = \frac{57 - 43}{\frac{90}{\sqrt{81}}}$ $z=(57-43)/(90/sqrt81)$

$= \frac{14}{\frac{90}{9}} = \frac{14}{10} = 1.4$ $=14/(90/9)=14/10=1.4$

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