27. Scores on a test have mean 70 and standard deviation 15. Let .1: denote a student 's score on this test. The professor wants to adjust the scores so that they have mean 75 and standard deviation 12. Let y denote a student's adjusted score. 1; is related to a: by y = a + be, and the professor wants to nd a and b so that the adjusted scores have the correct mean and standard deviation. What does a. have to be? (a) 5 (b) 0.8 (c) 19 (d) 10 J