ZTEST(ref,x)
ZTEST returns the two-tailed probability of a z-test.
@ref is the data set and @x is the value to be tested.
If @ref contains less than two data items ZTEST returns #DIV/0! error.
This function is Excel compatible.
Let us assume that the cells A1, A2, ..., A5 contain numbers 11.4, 17.3, 21.3, 25.9, and 40.1. Then
ZTEST(A1:A5,20) equals 0.254717826.
CONFIDENCE, NORMDIST, NORMINV, NORMSDIST, NORMSINV, STANDARDIZE.