Question

For women aged 18–24, systolic blood pressures (in mm Hg) are normally distributed with a mean of 114.8 and a standard deviation of 13.1. If 4 women in that age bracket are randomly selected, find the probability that their mean systolic blood pressure is greater than 140.

Answer 1

Take note of the formula for the z-score for mean:
\[z=\frac{ xbar - \mu }{ \frac{ s }{ \sqrt{n} } }\]