9.95 An experiment is conducted to determine whether a particular medicine administered to patients with neurological disorders has an effect on their systolic blood pressure. Theoretically, the presence of some of the chemicals in the medicine should result in an increase of blood pressure. A random sample of 8 patients is tested for their systolic blood pressure before and after taking the medicine. Standard deviations of the two populations are assumed to be equal to 6 mmHg. The data for the systolic blood pressure, in mmHG, are as follows:

Before the medicine After the medicine 125 136 117 124 126 126 132 137 128 139 120 124 131 132 122 126 Find a 90% confidence interval for the difference between the population means for the systolic blood pressure before and after the medicine, assuming that the populations are approximately normally distributed.