Question

For a Binomial distribution whose mean is 9 and S.D. is $\frac{3}{2}$, then the value of n equals

• A. $12$
• B. $36$
• C. $9$
• D. none of these

Answer 1

Answer: (A)

$12$

Fact: for Binomial Distribution
mean $=np=9$ and S.D. $=\frac{3}{2}$
$np=9$ and $npq=\frac{9}{4}$
$\therefore$ $q=\frac{1}{4}$, $p=\frac{3}{4}$
$\therefore$ $np=9$
$n=\frac{9\times 4}{3}=12$