Binomial distribution According to the Pew Research Center a

Binomial distribution: According to the Pew Research Center, approximately 60% of the U.S. adults have searched online for health information. Calculate the mean and variance of the number of U.S. adults who have searched online for health information for a sample of size 50.

Solution

Let X be a random variable denoting the number of U.S. adults who have searched online for health information.
X follows a binomial distribution with parameters n=50 and p=0.6

n = 50
p = 0.6
Mean = n*p = 50*0.6 = 30
Variance = n*p*(1-p) = 50*0.6*0.4= 12