The Oregon Health & Science University’s news website (www.ohsu.edu) gives information on a study that found that some commercial cigarette brands contain 10 to 20 times higher percentages of nicotine in the “free-base” form, that is, the form thought to be the most addictive. Consider another study designed to compare the nicotine content of two different brands of cigarettes. The nicotine content was determined for 25 cigarettes of brand A and 25 cigarettes of brand
b. The sum of ranks for brand A equals 688, and the sum of ranks for brand B equals 587. Use the Mann–Whitney U statistic to test the null hypothesis that the average nicotine content is the same for the two brands versus the alternative, that the average nicotine content differs. Use a = 0.01