Question

One particular day, tourteen students visiting the student health center for a free dental examination during National Dental Hygiene Month were asked how many months had passed since their last visit to a dentist. Their responses were x1, x2,...X14. We would like to construct a 98% confidence interval for the mean number of months elapsed since the last visit to a dentist for the population of students participating in the program, using this sample of 14 students. The formula for the confidence interval for the mean number of months in between visits to the dentist is it- where t is the t-critical value. To find the value of t-critical, we first must know the degrees of freedom for the t-distribution we need to use in this case. We must use degrees of freedom in this situation. Once we are clear about the degrees of freedom, we can compute the value of t-critical, the critical value for the t-distribution. t-critical = 40) (to three places after the decimal)