Question

If the sum of the mean and variance of a binomial distribution for 5 trials is 1.8, then p=......

• A. 0.18
• B. 0.2
• C. 0.8
• D. 0.4

Answer 1

Answer: (B)

0.2

Given number of trials $,n=5$

Sum of mean and variance of a binomial distribution is $1.8$

$⟹np+npq=1.8$

$⟹p(1+1-p)=\frac{1.8}{5}=0.36$

$⟹2p-p^2=0.36⟹p^2-2p+0.36=0$

$(p-1{)}^2=0.64⟹p=1-\sqrt{0.64}=1-0.8=0.2$