Dr. Ross Darrow believes that nicotine in cigarettes causes cigarette smokers to have higher daytime heart rates on average than do nonsmokers. He also believes that smokers crave the nicotine in cigarettes rather than just smoking for the physical satisfaction of the act and, accordingly, that the average smoker will smoke more cigarettes per day if he or she switches from a brand with a high nicotine content to one with a low level of nicotine. (a) Suppose Ross knows that nonsmokers have an average daytime heart rate of 78 beats per minute. What are the appropriate null and alternative hypotheses for testing his first belief? (b) For the past 3 months, he has been observing a sample of 48 individuals who smoke an average of 15 high-nicotine cigarettes per day. He has just switched them to a brand with a low nicotine content. State null and alternative hypotheses for testing his second belief.
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