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CUET · MATHS · PYQ PAPER 2023

If the mean of a binomial distribution is 12 and its standard deviation is 2 , then the number of trials is :

  1. A 18
  2. B 14
  3. C 24
  4. D 16
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Answer & Solution

Correct Answer

(A) 18

Step-by-step Solution

Detailed explanation

\(\mu = np = 12\) \(\sigma^2 = np(1-p) = 2^2 = 4\) \(12(1-p) = 4 \Rightarrow 1-p = \frac{4}{12} = \frac{1}{3} \Rightarrow p = 1-\frac{1}{3} = \frac{2}{3}\) \(n\left(\frac{2}{3}\right) = 12 \Rightarrow n = 12 \times \frac{3}{2} = 18\)
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