the distribution of SAT scores for college-bound male seniors has a mean of 1512 and the standard deviation of 322. the distribution of SAT scores for college-bound female seniors has amean of 1486and a standard deviation of 311. one male and one female are randomly selected. Assume their scores are independent. What is the average sum of their scores, what is the average difference of their scores and what is the standard deviation of the difference of their scores