Use the empirical rule to solve the problem. the systolic blood pressure of 18-year-old women is normally distributed with a mean of 120 mmhg and a standard deviation of 12 mmhg. what percentage of 18-year-old women have a systolic blood pressure between 96 mmhg and 144 mmhg

First you need to determine how much standard deviation the range is.

120+12*x = 96

x = 96-120 / 12 = - 2

120+12*y=144

y = 144-120/12 = + 2

Systolic blood pressure between 96 mmHg and 144 mmHg means that the blood pressure is at - 2SD to + 2SD. The Z-score for - 2SD is 0.0228 and + 2SD is 0.9772

So the percentage would be: 0.9772 - 0.0228 * 100% = 95.44%