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December 18, 2014

December 18, 2014

Posted by **Kristin** on Friday, September 28, 2012 at 4:07pm.

What is the probability that the average of this sample will be within 1.4 STANDARD ERRORS of the population mean?

- statistics -
**MathGuru**, Friday, September 28, 2012 at 6:24pmmean = 67.6

standard deviation = 4.2

sample size = 51

Standard error: sd/√n = 4.2/√51 = 0.588

Next step:

67.6 - 1.4 = 66.2

67.6 + 1.4 = 69

Use z-scores:

z = (x - mean)/sd

Therefore:

z = (66.2 - 67.6)/0.588 = -2.38

z = (69 - 67.6)/0.588 = 2.38

Finally:

Check z-table for the probability between the above two z-scores. This will be your answer.

I hope this helps.

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