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Question: Answered & Verified by Expert
A die is tossed thrice. If getting a four is considered a success, then the mean and variance of the probability distribution of the number of successes are
MathematicsProbabilityJEE Main
Options:
  • A $\frac{1}{2}, \frac{1}{12}$
  • B $\frac{1}{6}, \frac{5}{12}$
  • C $\frac{5}{6}, \frac{1}{2}$
  • D None of these
Solution:
2042 Upvotes Verified Answer
The correct answer is: None of these
We are given that $n=3, \quad p=\frac{1}{6}, \quad q=\frac{5}{6}$
Mean $=n p=3 \times \frac{1}{6}=\frac{1}{2}$
Variance $=n q p=3 \times \frac{1}{6} \times \frac{5}{6}=\frac{5}{12}$.

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