In a binomial distribution, the probability of getting success is $\frac{1}{4}$ and standard deviation is 3. Then it's mean is :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 12
$μ=np$
Variance: $σ^2=np(1-p)$
$σ=\sqrt{np(1-p)}=3$
$p=\frac{1}{4},q=\frac{3}{4}$
$\sqrt{npq}=\sqrt{n.\frac{3}{16}}=3$
$\frac{3n}{16}=9$ (squaring both side)
$3n=144$
$n=48$
$μ=48×\frac{1}{4}=12$