The mean of n observations is 
. If k is added to each observation, then the new mean is
Mean = (x1 + x2 + ...+ n terms)/N
= x1 + k + x2 + k +...+n terms/N
= Mean + k
= 
+ k
2
The mean of n observations is . If k is added to each observation, then the new mean is
Mean = (x1 + x2 + ...+ n terms)/N
= x1 + k + x2 + k +...+n terms/N
= Mean + k
= + k