Understanding Basic Statistics 6th Edition by Charles Henry Brase,Corrinne Pellillo Brase

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Critical Thinking Consider a binomial distribution of 200 trials with expect­ed value 80 and standard deviation of about 6.9. Use the criterion that it is unusual to have data values more than 2.5 standard deviations above the mean or 2.5 standard deviations below the mean to answer the following questions.
(a) Would it be unusual to have more than 120 successes out of 200 trials Explain.
(b) Would it be unusual to have fewer than 40 successes out of 200 trials Explain.
(c) Would it be unusual to have from 70 to 90 successes out of 200 trials Explain.