A normally distributed pdf of measurements of student's heights in a class of 100 resulted in a mean of 66 inches and a standard deviation of 3.5 inches. What is the variance of the distribution? The class then is split between men and women and two distributions are then created. The two distributions have means of 61 inches and 68 inches for women and men respectively. The pdf of women has a standard deviation of 3 inches and the pdf of men has a standard deviation of 4 inches. What are the two ranges of heights spanned within three standard deviations for the pdfs