If the mean of five observations x,x+2,x+4,x+6,x+8 is 11,find the mean of first three observations. answer =9. but how?
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Follow the steps
First take the mean of five obs.
(x +x+2+x+4+x+6+x+8)/5=11
5x + 20 = 11×5
5x +20 = 55
5x = 55 - 20
5x = 35
x = 7
By doing this we got the value of x.
Now take the first 3 obs.
x+x+2+x+4 (take the value of x and take out the mean)
That will be
(7+9+11)/3
= 27/3
= 9
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