Returns the onetailed probability of the chisquared distribution. The γ2 distribution is associated with a γ2 test. Use the γ2 test to compare observed and expected values. For example, a genetic experiment might hypothesize that the next generation of plants will exhibit a certain set of colors. By comparing the observed results with the expected ones, you can decide whether your original hypothesis is valid.
Syntax
CHIDIST(x,degrees_freedom)
X is the value at which you want to evaluate the distribution.
Degrees_freedom is the number of degrees of freedom.
Remarks

If either argument is nonnumeric, CHIDIST returns the #VALUE! error value.

If x is negative, CHIDIST returns the #NUM! error value.

If degrees_freedom is not an integer, it is truncated.

If degrees_freedom < 1 or degrees_freedom ≥ 10^10, CHIDIST returns the #NUM! error value.

CHIDIST is calculated as CHIDIST = P(X>x), where X is a γ2 random variable.
Example
X 
Degrees_freedom 
Formula 
Description (Result) 
18.307 
10 
=CHIDIST([X],[Degrees_freedom]) 
Onetailed probability of the chisquared distribution, for the specified arguments (0.050001) 