Apple iWork '09 - Manual (Page 277)

Chapter 10 Statistical Functions 277
NORMINV
The NORMINV function returns the inverse of the cumulative normal distribution.
NORMINV(probability, average, stdev)
 probability: A probability associated with the distribution. probability is a number
value and must be greater than 0 and less than 1.
 average: The average of the distribution. average is a number value representing
the known average (arithmetic mean) rate at which events occur.
 stdev: The standard deviation of the population. stdev is a number value and must
be greater than 0.
Usage Notes
If  average is 0 and stdev is 1, NORMINV returns the same value as the inverse of the
cumulative standard normal distribution returned by NORMSINV.
Example
=NORMINV(0.89, 15, 2.5) returns 18.0663203000915.
Related Topics
For related functions and additional information, see:
“NORMDIST” on page 276
“NORMSINV” on page 278
“Listing of Statistical Functions” on page 225
“Value Types” on page 36
“The Elements of Formulas” on page 15
“Using the Keyboard and Mouse to Create and Edit Formulas” on page 26
“Pasting from Examples in Help” on page 41
NORMSDIST
The NORMSDIST function returns the standard normal distribution.
NORMSDIST(num)
 num: A number. num is a number value.
Usage Notes
A standard normal distribution has an average (arithmetic mean) of 0 and a Â
standard deviation of 1.