British health officials have expressed concern about problems associated with vitamin D deficiency among certain immigrants. Doctors

Question:

British health officials have expressed concern about problems associated with vitamin D deficiency among certain immigrants. Doctors have conjectured that such a deficiency could be related to the amount of fiber in a person’s diet. An experiment was designed to compare the vitamin D plasma half-life for two groups of healthy individuals. One group was placed on a normal diet, whereas the second group was placed on a high-fiber diet. The accompanying table gives the resulting data (from “Reduced Plasma Half-Lives of Radio-Labeled 25(OH)D3 in Subjects Receiving a High-Fibre Diet,” British Journal of Nutrition [1993]: 213–216).

Use the following MINITAB output to determine whether the data indicate that the mean half-life is higher for those on a normal diet than those on a high-fiber diet. Assume that treatments were assigned at random and the two plasma half-life distributions are normal. Test the appropriate hypotheses using α = .01.