Question

the mean of n- observation is x . if constant a is subtracted from each observation, the show that the new mean x -a

Answer 1

let observations be a1,a2,a3...an
now the mean of n observation is x
(a1+a2+a3+...+an)/n=x
a1+a2+...an=xn
now as a isubtracted from each term and there r n terms therefore a is subtracted n times
a1-a+a2-a+...+an-a=xn-an
(a1-a+a2-a+...+an-a)/n=x-a=new mean

hope this helps:p