The following table lists some of the weights from Data Set 4 in Appendix B. Those weights were measured from college students in September and later in April of their freshman year. Assume that we plan to use the Wilcoxon signed-ranks test to test the claim of no difference between September weights and April weights. What requirements must be satisfied for this test? Is there any requirement that the populations must have a normal distribution or any other specific distribution? In what sense is this Wilcoxon signed-ranks test a €œdistribution-free test€?€ƒ

September weight 67 53 64 74 67 70 55 74 62 57 April weight 66 52 68 77 67 71 60 82 65 58