Apple iWork '09 - Manual (Page 276)

NORMDIST
The NORMDIST function returns the normal distribution of the specified function form.
NORMDIST(num, average, stdev, form-type)
 num: The number to be evaluated. num is a number value.
 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.
 form-type: A value that indicates which form of the exponential function to
provide.
cumulative form (TRUE or 1): Return the value of the cumulative distribution
function form.
probability density form (FALSE or 0): Return the value of the probability density
function form.
Usage Notes
If  average is 0, stdev is 1, and form-type is TRUE, NORMDIST returns the same value as
the cumulative standard normal distribution returned by NORMSDIST.
Examples
=NORMDIST(22, 15, 2.5, 1) returns 0.997444869669572, the cumulative distribution form.
=NORMDIST(22, 15, 2.5, 0) returns 0.00316618063319199, the probability density form.
Related Topics
For related functions and additional information, see:
“NORMINV” on page 277
“NORMSDIST” on page 277
“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
276 Chapter 10 Statistical Functions