Binomial Distribution. The Centers for Disease Control say that 30% of high school students smoke cigarettes. Suppose you randomly select 25 high school students and survey them about their attitudes on smoking, as well as ask them if they smoke. p = .30 N=25

a. What is the probability that at least 8 students smoke? P(X ? 8)?

b. What is that probability that exactly 5 students smoke? P(X=5)?

c. Calculate the mean, variance and standard deviation for this problem.

Mean

Variance

Standard Deviation

d. Suppose you asked a student to do a random survey and his sample of 25 students had 12 smokers. Does this feel like a rare event? Why? Another student said your survey worker asked students in a detention hall rather than randomly select from the lunch room, as you asked. Would this help understand the result?