Please solve it step by step

(no. 5 (2 points) A college student has just completed her junior year. The following table summarizes her grade-point average (GPA) for each of the past nine quarters: Year Semester GPA Freshman Fall 2.4 Winter 2.9 Spring 3.1 Sophomore Fall 2.5 Winter 3.0 Spring 3.2 Junior Fall 2.6 Winter 3.1 Spring 3.5 a) Forecast the student's GPA for all three semesters of her senior year by using ADM method. b) Forecast the student's GPA for all three semesters of her senior year by using MDM method. c) Which method gives more reliable forecast? Why