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# Probability and Variance

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The cell phone industry is growing at a rapid pace. Current estimates suggest that 60% of people have cell phones. Suppose 25 people were randomly and independently sampled. Let X be the number of people in the sample having cell phones. A) The variable X follows: aa) Normal distribution. bb) Continuous distribution. cc) Binomial distribution. dd) None of the above. I think it is cc) binomial distribution, but not sure. B) Which of the following are not possible values of X? aa)0 bb)30 cc)10 dd)20. I think it is bb)30, because there is only 25 peole in the sample, but I am probably wrong. C) What is the probability that fewer than half of these samples people currently have cell phones. I believe that in order to solve this part, one must use the binomal table, but I am not sure. D)What is the variance of the number of people in the sample of 25 currently having a cell phone.