Twenty-four experimental animals with vitamin D deficiency were divided equally into two groups.

Group 1 received treatment consisting of a diet that provided vitamin D. The second group was not treated. At the end of the experimental period, serum calcium determinations were made with the following results:

Treated group:
x ¼ 11:1 mg=100 ml;s ¼ 1:5 Untreated group:
x ¼ 7:8 mg=100 ml;s ¼ 2:0 Assume normally distributed populations with equal variances.