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In a set of 2 n observations, half of them are equal to ' a ' and the remaining hall are equal to ' - a ^ '. If the standard deviation of all the observations is 2 ; then the value of |a| is :

Options

  1. A2
  2. B2
  3. C4
  4. D2 2

Correct answer

A. 2

Step-by-step solution

Clearly mean A =0 Now, standard deviation = (x- A )^2 2 n aligned 2=& (a-0)^2+(a-0)^2+ +(0-a)^2+ . . 2 n &= a^2 2 n 2 n =|a| aligned Hence, |a|=2

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