Question

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

Answer 1

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

Explanation:

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.