6.5 Vasoconstrictor responses to the intra-arterial injection of epinephrine were ob- tained in the perfused hindpaws of dogs. Responses were obtained before and 30 minutes after the intramuscular (i.m.) administration of cocaine hydrochloride, 5 mg/kg i.m. Vasoconstriction was indicated by the increases in perfusion pressure. 210 COMPARISON OF TWO GROUPS: t-TESTS AND RANK TESTS Perfusion Pressure Dog (mm Hg) Number Precocaine Postcocaine 40 78 24 36 6 6 28 24 64 110 24 64 8 20 44 40 (a) Use a nonparametric test to test the hypothesis of equal response distributions pre- and postcocaine administration. Use a = 0.05. (b) What is the signed-rank estimate of Ha? (c) Place a 90% confidence interval on ud