According to an almanac, 60% of adult smokers started smoking before turning 18

Question

According to an almanac, 60% 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 200 trials of the probability experiment. (b) Interpret the mean. (c) Would it be unusual to observe 170 smokers who started smoking before turning 18 years old in a random sample of 200 adult smokers? Why? (a) Hx Ox-D (Round to the nearest tenth as needed.) (b) What is the correct interpretation of the mean? A. It is expected that in a random sample of 200 adult smokers, 120 will have started smoking before turning 18. O B. It is expected that in a random sample of 200 adult smokers, 120 will have started smoking after turning 18. O C. It is expected that in 50% of random samples of 200 adult smokers, 120 will have started smoking before turning 18. (c) Would it be unusual to observe 170 smokers who started smoking before turning 18 years old in a random sample of 200 adult smokers? 0 A. O B. ° C. 0 D. 0 E. No, because I 70 is greater than + 2 No, because 170 is between -2 and +2. Yes, because 170 is greater than +2. No, because 170 is less than -2 Yes, because 170 is between -2 and + 2.

Explanation / Answer

p = 0.6 n = 200

(a) x = np = 200*0.6 = 120

x = (np(1-p))

= (120*0.4)

= 48

= 6.9

(b) It is expected that in a sample of 200 smokers, 120 will have started smoking before turning 18.

(c) Would it be unusual to observe 170 smokers?

C. Yes, because 170 is greater then + 2.

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