The final grade of a student in this class is converted from a numerical average score calculated by the formula: S= 60% - T+ 40% E, where T = the average of the two better test scores, after dropping the lowest score of the three, and E= the score on the final exam. There was a 20% of an extra assignment #1 and #2 added to the tests No.1 and 2, respectively. So far, Ethan's scores for three in-class test and two extra assignments are: T = 80, A, 90, T-57. A,= 85, and T-74. Also T, is curved by y = 10 vx. (b) If his score for the final exam is 76, what is Ethan's course average score? (c) What score, E (range of 0-100), should Ethan obtain on the final exam in order for him to receive a letter grade B' or better (Numerical average 2 87)? (d) Is it possible for him to receive a grade A (Numerical average 2 93)? why or why not?