Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying table (based on data from "Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme", by MacGregor et al., BMJ, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril has an effect on systolic blood pressure? Explain in a sentence why statistical methods from Chapters 7 & 8 (of instructor's notes) - Z-interval, Z-test, T-interval or I-test -cannot be used for this problem. Then, use the sign test to conduct the required test. Subject A B C D E F G H I J K L Before 200 174 198 170 179 182 193 209 185 155 169 210 After 191 170 177 167 159 151 176 183 159 145 146 177