XI.2 (extra credit, 5 pts.) A certain longitudinal Framingham Offspring Study involves examination of participants every four years. The following data represent the systolic blood pressures of a subsample of 10 participants in the 6th and 7th examinations. Is there evidence that the population mean change in the systolic blood pressures is different from zero? Use a 90% confidence level. Explain why pairing is necessary in this problem. Assume the population of changes (differences) in blood pressure is approximately normal. Subject 1 2 3 4 5 6 7 8 9 10 6th Examination 111 135 127 155 115 125 123 140 137 143 7th Examination 119 122 127 135 123 113 106 131 142 131