Maria, a college student, is getting ready for three final examinations at the end of the school year. Between now and the start of exams, she has 15 hours of study time available. She would like to get as high a grade average as possible in her math, physics, and engineering economy classes. She feels she must study at least 2 hours for each course and, if necessary, will settie for the low grade that the limited study would yield. How much time should Maria devote to each class if she estimates her grade in each subject as follows:

Engineering Mathematics Physics Economy Study Study Study Grade Hours Hours Grade Hours Grade 25 2 35 50 3 35 3 41 61 4 44 4 49 4 71 5 52 5 59 5 79 6 59 6 68 86 65 77 92 70 85 96