The observations $$x_i(i = 1, 2, ... ... ... ..., 15)$$ of an experiment it is given $$\sum_{i=1}^{15} x_i = 170$$ and $$\sum_{i=1}^{15} x_i^2 = 2830$$. Laterit is noticed that one x; is entered as 20 instead of the correct value 30. The correct value of their variance is

A

78

B

8.33

C

188.66

D

177.33