[question removed by admin]
The book says that for both A and B, we can make no such statement because we are not told of how the population is distributed. The answer says: [answer removed by admin] Which I believe is saying that the sample of analysts estimates is not a good enough way to determine distribution. Even though B. has what the book considers to be a “large” sample size (i.e. ≥30) it’s still not sufficient to answer the question.
For C and D, their explanations are a bit different. They say that [answer removed by admin] That’s fair enough - with a normal distribution and a known variance you can solve with a z-statistic, but then they say that with a sample size of 60 we can make a statement about the confidence interval. Now, it must have something to do with the fact that C and D are looking for a probabilistic statement (and unfortunately, the book barely talks about probabilistic statements) but I would think that because distribution is unknown, we wouldn’t be able to make a determination either way.