The economics department implemented a new grading policy, where the student's overall score is the minimum of the number of correct answers the student gets on two exams. The student's utility function is U(S, M)=S-[(1/2)A(M^2)], where S is the student's overall score for the course, M is the number of minutes spend studying, and A is a variable that reflects how much the student dislikes studying. For the first exam, each correct answer costs student 10 mins of study time. For the second midterm, each correct answer costs student 20 mins of study time. We know the student studied for 1200 mins. What is the value of A in this student's utility function?