Question

If A.M is 40 observations of variable is 25 and S.D is 4 . The sum of square all observation is

Answer 1

Answer:

25624

Step-by-step explanation:

A.M (arithmetic mean )= 25

S.D (standard deviation)= 4

n (sample size) = 40

The formula for variance S^2 is

$S^2=\frac{1}{n-1}*\sum (x_i- \bar x)^2\\ \\S^2=\frac{1}{n-1}*[ \sum x_i^2- n \bar x ^2]$

the second equation is a simplified from of the former.

Now, we substitute the values given and make the missing value the subject of the formula as;

$4^2=\frac{1}{40-1}*[ \sum x_i^2 - 40*25^2]\\ 16=\frac{1}{39}*[\sum x_i^2 -25000]\\\\ 16*39=\sum x_i^2 -25000\\\\\sum x_i^2=16*39+25000\\\\\sum x_i^2=25624$

Therefore, The sum of square all observation is  25624

Answer 2

Answer:

The answer is 25640 there was an small mistake in the calculation weresle 1\n -1 is not the formula and the formula is 1/n

Step-by-step explanation: