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A box contains 6 pens , 2 of which ...

A box contains 6 pens , 2 of which are defective Two pens are taken randomy from the bax .If r,v. X., : Number of defective pens obtained , then standard deviation of x=

A

`+- (4)/(3sqrt(5))`

B

`(2)/(3)`

C

`(16)/(45)`

D

`(4)/(3sqrt(5))`

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The correct Answer is:
B
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