For a medical study, a researcher wishes to select people in the middle 90% of the population based on blood pressure. If the mean systolic blood pressure is 120 and the standard deviation is 8, find the upper and lower readings that would qualify people to participate in the study.
Here are the answers, but be sure to SHOW YOUR WORK or explain your solution process.
Answer: Between 106.84 and 133.16, or 107 to 133 when rounded.