6. (20 points) 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 (based on data from the National Health Survey). Hypertension is commonly defined as a systolic blood pressure above 140. (a) If a single women between the ages of 18 and 24 is randomly selected, find the probability that her systolic blood pressure is greater than 140. (b) If 4 women in that age bracket are randomly selected, find the probability that their mean systolic blood pressure is greater than 140