A researcher is interested in finding a 95% confidence interval for the mean number minutes students are concentrating on their professor during a one hour statistics lecture. The study included 143 students who averaged 41.7 minutes concentrating on their professor during the hour lecture. The standard deviation was 11.2 minutes. Round answers to 3 decimal places where possible.

a. To compute the confidence interval use a _____ ( z or t) distribution.

b. With 95% confidence the population mean minutes of concentration is between ____and____ minutes.

c. If many groups of 143 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.