MCQ 12 Marks
If the mean and variance of a binomial distribution are 5 and 2.5 respectively, then $n=$
- A5
- B10
- C18
- D15
Answer
View full question & answer→Given: Mean = np = 5 ....(1)
Variance = npq = 2.5 ....(2)
Dividing (2) by (1): $\frac{n p q}{n p}=\frac{2.5}{5} \therefore q=\frac{1}{2}$
$\therefore p=1-q=1-\frac{1}{2}=\frac{1}{2}$
From (1): np = 5,
$\therefore n\left(\frac{1}{2}\right)=5, \therefore n=10$