Question

Mr. Patrick teaches math to 1515 students.
He was grading tests and found that when he graded everyone's test except Payton's, the average grade for the class was 8080.
After he graded Payton's test, the test average became 81.
What was Payton's score on the test?

Answer 1

Sum of all grades / number of students = average grade

Average grade = 80
number of students = 1514 (excluding payton)

80 * 1514 = 121120

Average grade = 81
number of students = 1515

81 * 1515 = 122715

Sum of 1515 students = 122715
Sum of 1514 students = 121120
Difference:                          1595   *Paytons grade