Question:

The maximum value of the variance of Binomial distribution with parameters \(n\) and \(p\) is:

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For a Binomial distribution, \[ \mathrm{Var}(X)=np(1-p). \] The expression \(p(1-p)\) attains its maximum value \(\frac14\) at \(p=\frac12\).
Updated On: Jun 26, 2026
  • \(\frac{1}{2}\)
  • \(\frac{n}{4}\)
  • \(np(1-p)\)
  • \(2n\)
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The Correct Option is B

Solution and Explanation

Step 1: Recall the variance of a Binomial distribution.
If \[ X\sim B(n,p), \] then the variance is \[ \mathrm{Var}(X)=np(1-p). \]

Step 2: Maximize the expression \(p(1-p)\).
Consider \[ f(p)=p(1-p). \] Expanding, \[ f(p)=p-p^2. \] This is a downward-opening parabola whose maximum occurs at \[ p=\frac{1}{2}. \] Substituting, \[ f\!\left(\frac12\right) = \frac12\left(1-\frac12\right) = \frac14. \]

Step 3: Obtain the maximum variance.
Substituting the maximum value of \(p(1-p)\) into the variance formula, \[ \mathrm{Var}(X)_{\max} = n\left(\frac14\right) = \frac{n}{4}. \]

Step 4: Final conclusion.
Therefore, the maximum value of the variance is \[ \boxed{\frac{n}{4}}. \]
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