Can someone help me please?
posted by Jennifer on .
A set of 50 data values has a mean of 15 and a variance of 25. Find the standard score of a data value = 20

The "standard score" is more commonly called the "zscore".
It is the number of "standard deviations" above the mean.
The standard deviation is the square root of the variance, or 5 in this case.
The number of data values is not needed to answer the question.
A data point of 20 is one standard deviation above the mean of 15, so the standard or "z" score is 1.0 
Statistics confuses me....thank you for your help :)

A zscore is 0.6 standard deviations above the mean.