A researcher is interested in finding a 90% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 148 students who averaged 37.6 minutes concentrating on their professor during the hour lecture. The standard deviation was 12.2 minutes.

a. To compute the confidence interval use a? Z OR Tdistribution.

b. With 90% confidence the population mean minutes of concentration is between(round to 3 decimal places ) ____ and _______minutes.

c.If many groups of 148 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 minutes of concentration and about___________percent will not contain the true population mean minutes of concentration.