a. To compute the confidence interval use a ? distribution.

b. With90% confidence the population mean number of visits per week is between___ and ___ visits.

c.If many groups of 275 randomly selected members are studied, then a different confidence interval would be produced from each group. About _____ percent of these confidence intervals will contain the true population mean number of visits per week and about _____ percent will not contain the true population mean number of visits per week.