z = (x - mean)/ sigma
z = (80 - 70)/15
= 10/15
= 2/3 = .666666666666667 :)
If there is more, use
http://davidmlane.com/hyperstat/z_table.html
A set of data items is normally distributed with a mean of 70. Convert the data item to a z-score, if the standard deviation is as given.
data item: 80; standard deviation: 15
3 answers
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