1. The distribution of grades for various classes taught by different professors is given in the following table. Test the null hypothesis that the grade distributions are homogenous for these three professors at a significance level of = 0.05. (11 marks)

	Professor
Grade	Einstein	Rutherford	Bohr
A	18	36	20
B	25	44	15
C	85	73	82
D	17	12	8