Given that X is a binomial random variable with n 20 and p

Given that X is a binomial random variable, with n * 20 and p - 0.6. compute the mean, variance and standard deviation. A random sample of 15 people is taken from a population in which 40% favor a particular political candidate. What is the Binomial probability that exactly 9 individuals out of the 15 in this sample favor this candidate?

Solution

29.

Mean = np = 20*0.6 =12

Variance = npq = 20*0.6*0.4=4.8

Standard deviation is sqrt(4.8) = 2.19

20

X~B(15,0.4)

P(X=9) = binomdist(9,15,0.4,0) = 0.061

Binomdist is excel function

29. Mean = np = 20*0.6 =12 Variance = npq = 20*0.6*0.4=4.8 Standard deviation is sqrt(4.8) = 2.19 20 X~B(15,0.4) P(X=9) = binomdist(9,15,0.4,0) = 0.061 Binomdist is excel function