Solution: (a) if 200 adult smokers are randomly selected, how many would we expect to have started smoking before turning 18 years old?
Answer: It is expected that in a random sample of 200 adult smokers, [tex] 0.70 (200)=140 [/tex] will have started smoking before turning 18.
(b) would it be unusual to observe 160 smokers who started smoking before turning 18 years old in a random sample of 200 adult smokers? why?
Answer: Yes, it would be unusual to observe 160 smokers who started smoking before turning 18 years old in a random sample of 200 adult smokers, because 160 is greater than μ + 2σ
