Statistics Help!

9 The mean wait time for a drive-through chain is 193.2 seconds with a standard deviation of 29.5 seconds. What is the probability that for a random sample of 45 wait times, the mean is between 185.7 and 206.5 seconds? Identify the type of sampling (stratified, systematic, convenience, or cluster) that best describes each of the following cases: 10. (a) In order to complete a statistics project, a student passes out surveys to the first 50 people the student finds in the student union. (b) The FDA chooses 30 hospitals around the country at random. Every doctor in a chosen hospitals is asked to participate in the study. (c) Fifteen students from each of 10 on-campus sections of College Algebra are asked about the quality of the textbook used in the course. 11. Using Excel, calculate the appropriate critical value for each of the following confidence levels: (sample size 40) (a) z-value for 90% confidence level: ( b ) t-value for 99% confidence level: 12. A 95% confidence interval for a situation is developed and is given as follows: 35.94