A team of researchers interested in reducing alcohol-related problems in college fraternity members asked 159 members to report the number of drinks consumed on a typical occasion (Larimer et al., 2001). The mean number of drinks in their sample was 4.93, with a standard deviation of 2.73. Calculate a 95% confidence interval for this set of data.

a. State the desired level of confidence.

b. Calculate the confidence interval and confidence limits.

(1) Calculate the standard error of the mean (s_X̅).

(2) Calculate the degrees of freedom (df) and identify the critical value of t.

(3) Calculate the confidence interval and confidence limits.

c. Draw a conclusion about the confidence interval.