The mayor is interested in finding a 90% confidence interval for the mean number of pounds of trash per person per week that is generated in city. The study included 246 residents whose mean number of pounds of trash generated per person per week was 32.1 pounds and the standard deviation was 8.5 pounds.

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

b. With90% confidence the population mean number of pounds per person per week is between and pounds.

c.If many groups of 246 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 pounds of trash generated per person per week and about percent will not contain the true population mean number of pounds of trash generated per person per week.