According to an almanac, 80% of adult smokers started smoking before turning 18

Question

According to an almanac, 80% of adult smokers started smoking before turning 18 years old. When technology is used, use the Tech Help button for further assistance. (a) Compute the mean and standard deviation of the random variable X, the number of smokers who started before 18 in 100 trials of the probability experiment. (b) Interpret the mean. (c) Would it be unusual to observe 85 smokers who started smoking before turning 18 years old in a random sample of 100 adult smokers? Why? (a) mu _x = ____

Explanation / Answer

a) mean =np =100*0.8=80

std deviaiton =(np(1-p)1/2 =4

b) interpreation: please provide option for that.

c)P(X>=85) =P(Z>(84.5-80)/4)=P(Z>1.125)=0.1303

as probability of above is greater then 0.05 level ; therefore it is not unusual.

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