1. ## Variance

The fomula u = x + 20 is used to find the standard deviation of the values of x given in a frequency table. It is found that "summation Fi = 40", "summation ui fi = 112 and "summation ui squared fi = 10208. Find the variance and mean values of x.

im so confused about the u = x +20

2. there is no effect on variance by the change u=x+20

variance of u= $\frac{1}{n}(\sum_{i=1}^{n}(u_i-u_{mean})^2*f_i)$
$n=\sumf_i=40$
solving we get
variance of u=248.44
hence, variance of x=248.44

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