According to the American Lung Association, 90% of adult smokers started smoking before turning 21 years old. Ten smokers 21 years old or older are randomly selected, and the number of smokers who started smoking is recorded. a. Find the probability that more than 8 of them started smoking before 21 years of age. (2-points) n=10p.09x=8P(x>8)=8(x=9)+p(x=10)=(nx)(p)x(18)nx=(109)(0.9)1(10.9)109+(1010)(0.9)10(10. 9)1010(10)(0.9)(0.1)+(1)(0.9)10(1) b. Find the expected value and standard deviation for the number of smokers (out of the ten) who started smoking before the age of 21. (2-points).
According to the American Lung Association, 90% of adult smokers started smoking before turning 21 years old. Ten smokers 21 years old or older are randomly selected, and the number of smokers who started smoking is recorded. a. Find the probability that more than 8 of them started smoking before 21 years of age. (2-points) n=10p.09x=8P(x>8)=8(x=9)+p(x=10)=(nx)(p)x(18)nx=(109)(0.9)1(10.9)109+(1010)(0.9)10(10. 9)1010(10)(0.9)(0.1)+(1)(0.9)10(1) b. Find the expected value and standard deviation for the number of smokers (out of the ten) who started smoking before the age of 21. (2-points).