Robert knows from reading his syllabus in intermediate algebra that the average of his chapter tests accounts for 80% (0.8) of his overall course grade. He also knows that the final exam counts as 20% (0.2) of his grade. Part 1 of 2 (a) Suppose that the average of Robert's chapter tests is 98%. Determine the range of grades that he would need on his final exam to get an "A" in the class. (Assume that a grade of "A" is obtained if Robert's overall average is 90% or better.) Robert would need % or better on his final exam. X 5 Part 2 of 2 (b) Determine the range of grades that Robert would need on his final exam to get a "B" in the class. (Assume that a grade of "B" is obtained if Robert's overall average is at least 80% but less than 90%.) Robert will receive a "B" in the class if he scores at least % and less than % on his final exam. X