"@Home" wrote:
>
> I am trying to solve a ? which basically gives the following facts:
>
> population of unknown number
> popu std dev of 27
> pop mean of 78
With what underlying distribution?
> sample of size n=81
> 2000 random samples
>
> The ? is:
>
> what is the sample mean?
> what is the std error (std dev of sample means)
> what shape would the histogram be?
How can you possibly know this without having the actual
sample? It's a random variable, it depends on your
sample.
>
> The sample mean is obviously 78 and I calculate the std error of the sample
> means to be 3.
The sample mean is the average of your actual sample
values. It isn't "obviously" 78 or anything else, though
it might be close to 78. And how did you calculate the standard
error?
>
> However I can't put the whole picture together. I suspect the distrib would
> be normal given the 81 samples, but is 3 a low number for a std error.
Now I'm really lost. From the fact that there are 81 samples,
you conclude the distribution is normal? And all you
know about the samples is that there are 81 of them?
>
> Is it possible to translate it into a z score without any addtional data.
It isn't possible to say anything at all without additional data.
- Randy
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