Statistics And Probability Question 502

Question: The mean and variance of a binomial distribution are 6 and 4. The parameter n is

[MP PET 2000]

Options:

A) 18

B) 12

C) 10

D) 9

Show Answer

Answer:

Correct Answer: A

Solution:

  •         Given  $ np=6,\,npq=4 $             \  $ \frac{npq}{np}=\frac{4}{6}\Rightarrow \,q=\frac{2}{3} $  and  $ p=\frac{1}{3} $                   $ \because  $  $ np=6\,\Rightarrow \,n\times \frac{1}{3}=6 $   
    

$ \Rightarrow ,n=18 $ .