Jack needs an exam average of at least 75 to pass his math course. (Range)

Question

Jack needs an exam average of at least 75 to pass his math course. All five exams are weighted equally and are worth 100 points each. He has earned the following scores on exams so far in the course: 80, 90, 75, and 60. What is the range of scores (written in algebraic notation) that he needs to earn on the final exam to have an average of at least 75 for the course?

Answer 1

Jack needs a total of 5*75=375 points.

Jack has 80+90+75+60=305 total points.

375-305=70 points at least needed on the final exam

or,...

(80+90+75+60+x)/5=75

305+x=5*75

305+x=375

x=375-305

x=70

since you can get up to 100 points on the exam, Jack can get between 70 and 100 points inclusive

x=Jack's score on the final exam

70≤x≤100