=CHITEST( actual, expected )
=CHITEST(A1:A3,{20,15,15})
The χ² statistic for the data indicated is 2.5 with 2 degrees of freedom; leading to a result value of 0.2865.
The CHITEST function is used to calculate the chi-squared value of a given distribution. It can be used to assess the difference between observed and expected results.