The chick wts data set presents the results of an experiment in which chickens are fed six different feeds. If we assume that the chickens were assigned to the feed groups at random, then we can assume that the chickens can be thought of as coming from one population. For each feed, we can assume that the chickens fed that feed are a random sample of the (theoretical) population that would result from feeding all chickens that feed.

a) For each of the six feeds, compute 95% confidence intervals for the mean weight of chickens fed that feed.

b) From an examination of the six resulting confidence intervals, is there convincing evidence that some diets are better than others?

c) Since you no doubt used the t-distribution to generate the confidence intervals in a), you might wonder whether that is appropriate. Are there any features in the data that suggest that this might not be appropriate?