QuestionRefer to the accompanying data display that results from a simple random sample of times (minutes) between eruptions of the Old Faithful geyser. The confidence level of $95 \%$ was used. Complete parts (a) through (d) below.
TInterval $$\begin{array}{l} (85.74,91.76) \\ x=88.75 \\ S x=8.897431411 \\ n=36 \end{array}$$ a. What are the requirements for using the methods for the mean to construct a confidence interval estimate of a population mean? A. The sample is a simple random sample and the population is normally distributed or $n \leq 30$. B. The sample is a simple random sample, the population is normally distributed, and $n>30$. C. The sample is a simple random sample, the population is normally distributed, and $n \leq 30$. D. The sample is a simple random sample and the population is normally distributed or $n>30$. b. What does it mean to say that the confidence interval methods for the mean are robust against departures from normality? A. The methods do not work well with distributions that are not normal. have only one mode, and should not include outliers. C. The methods only work with distributions that are not normal. should include outliers.