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A bag contains 30 white balls and 10 red balls. 16 balls are drawn one by one randomly from the bag with replacement. If X be the number of white balls drawn, then ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ X of deviation standard X of mean is equal to :

1. 4
2. 2 3
3. 3 3 4
4. 3 4

Correct answer: 2 3

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