JEE Math Practice Question
In a series of 2n observations, half of them equal $$a$$ and remaining half equal $$–a$$. If the standard deviation of the observations is 2, then $$|a|$$ equals
- A.2
- B.$$\sqrt 2 $$
- C.$${1 \over n}$$
- D.$${{\sqrt 2 } \over n}$$
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