A Note The reader may note that if each observation is multiplied by a constant k , the variance of the resulting observations becomes k times the original variance. Example17 The mean of observations is . and their variance is . .
If three of the observations are , and , find the other two observations. Solution Let the other two observations be x and y . Therefore, the series is , , , x , y. Now Mean x = .
= or = + x + y Therefore x + y = ... ( ) Also variance = . = n i