The mean score for freshmen on an aptitude test at a certain college is 530, with a standard deviation of 70. Assume the means to be measured to any degree of accuracy. What is the probability that two groups selected at random, consisting of 45 and 70 students, respectively, will differ in their mean scores by (a) more than 16 points? (b) an amount between 4 and 11 points? Click here to view page 1 of the standard normal distribution table. Click here to view page 2 of the standard normal distribution table. (a) The probability the difference is more than 16 points is (Round to four decimal places as needed.)