What is the z-score of sample X, if $n = 64, mu= 56, SD =20, and E[X] =320$ ?

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Answer 1 · 2015-11-13T06:01:35

I believe the $sum(x)=320$ is wrongly given.

There are 64 observations. The Total of the 64 observations cannot be $sum(x)=320$

Any the steps involved are -

$sum(x)=320$
$barx=(sum(x))/n=320/64=5$

$SE=sigma/(sqrtn)=20/sqrt(64)=20/8=2.5$

$z=(barx-mu)/(SE)=(5-56)/2.5=-20.4$

This answer may be wrong because of wrong information.

What is the z-score of sample X, if n = 64, mu= 56, SD =20, and E[X] =320n = 64, mu= 56, SD =20, and E[X] =320?