Question

The mean and variance of a binomial distribution are 4 and 2 respectively. Then the probability of 2 successes is
Select one:
a. 128/256
b. 28/256
c. 37/256
d. 217/256

Answer 1

Answer:

potion b

Step-by-step explanation:

given mean np=4

variance npq=2

v

we know that sum of probability is =1

p+q =1

now by replacing q by 1-p

we get p=0.5

sub p=0.5 in np=4 they gives n=8

now p+q=1 which implies q=0.5

therefore p=0.5,q=0.5 and n=8

the probability of success 2

which can be expressed as p(x=2)

by using ncx p^x(1-p)^n-x

by substituting the values we can get the final answer as 28/256