Refer to Data Set 1 in Appendix B and use the systolic blood pressure levels for males.

a. Using the systolic blood pressure levels for males, find the mean and standard deviation, and verify that the data have a distribution that is roughly normal.

b. Assuming that systolic blood pressure levels of males are normally distributed, find the 5th percentile and the 95th percentile. (Treat the statistics from part (a) as if they were population parameters.) Such percentiles could be helpful when physicians try to determine whether blood pressure levels are too low or too high.