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AP EAMCET2005MathematicsProbability

For a binomial variate X with n=6 , if P(X=2)=9 P(X=4) , then its variance is

Options

  1. A8 9
  2. B1 4
  3. C9 8
  4. D4

Correct answer

C. 9 8

Step-by-step solution

Given that n=6 and aligned & P(X=2)=9 P(X=4) ^6 C₂ p^2 q^4 & =9 ^6 C₄ p^4 q^2 aligned aligned 9 p^2 & =q^2 p & = 1 3 q aligned We know that p+q=1 aligned & q 3 +q=1 & q= 3 4 and p= 1 4 & variance =n p q=6 1 4 3 4 = 9 8 aligned

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