Volunteers who had developed a cold within the previous 24 hourswere randomized to take either zinc or placebo lozenges every 2 to3 hours until their cold symptoms were gone. Twenty-fiveparticipants took zinc lozenges, and 23 participants took placebolozenges. The mean overall duration of symptoms for the zinclozenge group was 4.5 days, and the standard deviation of overallduration of symptoms was 1.1 days. For the placebo group, the meanoverall duration of symptoms was 8.6 days, and the standarddeviation was 1.8 days.

(a) Calculate a 95% confidence interval for the mean overallduration of symptoms if everyone in the population were to take thezinc lozenges. (Round your answers to two decimal places.) todays

(b) Calculate a 95% confidence interval for the mean overallduration of symptoms if everyone in the population were to take theplacebo lozenges. (Round your answers to two decimal places.) todays

(c) On the basis of the intervals computed in parts (a) and (b),is it reasonable to conclude generally that taking zinc lozengesreduces the overall duration of cold symptoms more than if taking aplacebo? Explain why you think this is or is not an appropriateconclusion. Correct: Your answer is correct. reasonable to concludethat taking zinc lozenges reduces the duration of symptoms. Theconfidence intervals computed in parts (a) and (b) Correct: Youranswer is correct. , so a reasonable conclusion is that in apopulation of cold sufferers the mean duration of symptoms if zinclozenges are taken is Correct: Your answer is correct. than themean duration if placebo is taken.

(d) In their paper, the researchers say that they checkedwhether it was reasonable to assume that the data were sampled froma normal curve population and decided that it was. How is thisrelevant to the calculations done in parts (a) and (b)? Forrelatively Correct: Your answer is correct. samples such as these,a necessary condition (in theory) is that the population ofmeasurements has a normal distribution.