Consider the data from Exercise 6.3.10. If the sample size is small, as it is in this case, then in order for a confidence interval based on

Consider the data from Exercise 6.3.10. If the sample size is small, as it is in this case, then in order for a confidence interval based on Student’s distribution to be valid, the data must come from a normally distributed population. Is it reasonable to think that difference in HBE level is normally distributed? How do you know?