4. (15 points) (Demographics: height) The heights of adult American women are approximately normally distributed with a mean of 63.5 in and a standard deviation of 2.5 in. (a) Compute the proportion of adult American women whose height is between 61 in and 60 in. (b) Compute the proportion of adult American women whose height is greater than 66 in. (c) Compute the proportion of adult American women whose height is less than 62 in. (Hint: You won't be able to use the empirical rule for part (c).)