Question

mean of 9 observation is 135 if each observation is multiplied by 3 find the new mean.

Answer 1

Let the observations be ;
x1,x2,x3,x4,x5,x6,x7,x8,x9

then Mean =
(x1+x2+x3+x4+x5+x6+x7+x8+x9) / 9
135×9 = (x1+.....+x9)
(x1+...+x9) = 1215

If each observation is multiplied by 3 ;
then Mean =
(3x1+3x2+3x3+3x4.... +3x9)/9
= 3(x1+...+x9)/9
= (x1+...+x9)/3

= 1215/3
= 45
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