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If _ i=1 ^9 (x_i-5 )=9 and _ i=1 ^9 (x_i-5 )^2=45 , then the standard deviation of the 9 items x₁, x₂ , x₉ is

Options

  1. A9
  2. B4
  3. C3
  4. D2

Correct answer

D. 2

Step-by-step solution

aligned & Given, _ i=1 ^ y (x_i-5 )=9 & x_i-45=9 x_i=54 aligned Also, _ i=1 ^9 (x_i-5 )^2=45 aligned & x_i^2-10 54+25 9=45 & x_i^2=360 aligned Standard deviation ( )= 360 9 - ( 54 9 )^2 =2 .

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