Question

According to an​ almanac, 60% of adult smokers started smoking before turning 18 years old.

A)Compute the mean and standard deviation of the random variable​ X, the number of smokers who started smoking before 18 based on a random sample of 200 adults.
B) Interpret the mean.

Answer 1

A) mean = np
0.6(200) = 120
SD^2= np(1-p)
SD = sqrt(200(0.6)(1-0.6))
SD = 6.928
B) the mean of binomial distribution in this case is the average number of samples you’ll have to take before you achieve a sample of 200 where 60% of smokers who started smoking before 18.