For a particular medical study a researcher wishes to study
For a particular medical study a researcher wishes to study the middle 50% of the population based on systolic blood pressure. If the mean systolic blood pressure is 120 and the standard deviation is 12, what is the upper systolic blood pressure reading that would qualify people to be in the study?
Solution
50% of the distribution lies within 0.67448 standard deviations of the mean.
Thus, required x score is:
120+0.67448*12
=128.09

