Can I have help with this?

According to a data source, 92% of adult smokers in the US started smoking before turning 21 years old. Nine smokers 21 years old or older are randomly selected, and the number of smokers who started smoking before 21 is recorded. Let X denote the random variable that represents the number of smokers who started smoking before they were 21 years old. a) [2*4=8 points] Explain why this is a binomial experiment. b) [8 points] Find the probability that exactly five smokers started smoking before 21 years of age. c) [8 points] Find the probability that at least seven smokers started smoking before 21 years of age