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Mean of 5 observations is 7 . If four of these observations are 6,7,8,10 and one is missing then the variance of all the five observations is :

Options

  1. A4
  2. B6
  3. C8
  4. D2

Correct answer

D. 2

Step-by-step solution

Let 5 th observation be x . Given mean =7 aligned & 7= 6+7+8+10+x 5 & x=4 aligned Now, Variance gathered = (6-7)^2+(7-7)^2+(8-7)^2+(10-7)^2+(4-7)^2 5 = 1^2+0^2+1^2+3^2+3^2 5 = 20 5 = 4 =2 gathered

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