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A data consists of n observations `x_(1), x_(2), ..., x_(n). If Sigma_(i=1)^(n) (x_(i) + 1)^(2) = 9n and Sigma_(i=1)^(n) (x_(i) - 1)^(2) = 5n`, then the standard deviation of this data is

A

5

B

`sqrt(5)`

C

`sqrt(7)`

D

2

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The correct Answer is:
B
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