A cross over trial is conducted to compare an experimental medication for migraine headaches to a currently available medicine. A total of 50 patients are enrolled in the study and each patient receives both treatments. The outcome is the time in minutes until the headache pain resolves. Following each treatment, patients record the time it takes until pain is recorded. Treatments are assigned in random order (i.e., some patients receive the currently available medication first and then the experimental medication, and others receive the experimental medication first and then the currently available medication). The mean difference in times between the experimental and currently available medication is -9.4 minutes with a standard deviation of 2.8 minutes. Construct a 95% CI for the mean difference in times between the experimental and currently available medication.