MCQ
In a binomial distribution the probability of getting a success is $\frac{{1}}{{4}}$ and standard deviation is $3$, then its mean is
- A$6$
- B$8$
- ✓$12$
- D$10$
Probability of unsuccess $q = \frac{3}{4}$
Mean $= np$
Standard deviation $= \sqrt {{\rm{Variance }}} $
$ \Rightarrow $ Variance $= 9$
$⇒ npq = 9 ⇒ n.\,\frac{1}{4}.\,\frac{3}{4} = 9 ⇒ n = 48$
Mean $ = np$ $ = \frac{1}{4} \times 48 = 12$.
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