Question

If the sum of mean and variance of $B.D.$ for $5$ trials is $1.8$, the binomial distribution is

• A. $(5,0.8,0.2)$
• B. $(5,0.2,0.8)$
• C. $(10,0.8,0.2)$
• D. $(10,0.2,0.8)$

Answer 1

Answer: (B)

$(5,0.2,0.8)$

It is given that $n=5$
Therefore
Sum of Mean and variance implies
$np+np(1-p)$
$=np(2-p)$
$=5p(2-p)$
$=1.8$
$p(2-p)=\frac{9}{25}$

$p(2-p)=0.36$
$p(2-p)=0.2(2-0.2)$
Hence $p=0.2$
$1-p=0.8$
And $n=5$