Need formula. 4. Answer all of the following questions using Excel function(s). (5 pts each, 25 pts in total) 2 a. Compute the average of midterm and final exam grades for each student (use one decimal) 3 b. Assign grades: A if avg >=90, B if avg >=80, C if avg >=70. D if avg >=60, and F otherwise. 4 c. Label "Excellent" if both midterm and final >=90. 5 d. Label "Good" If either midterm or final >>#90. 6e. Mark if the average