Class Average

Johnny was ill and had to take a test a day late. His 96 raised the class average from 71 to 72. How many students, including Johnny, took the test?
Source: NCTM Mathematics Teacher 2006

Let a_1,a_2,a_3,\cdots,a_n represent the scores of the students.
By definition of average
Johnny’s 96 score raised the class average to 72
Number of students including Johnny

Answer: 25


About mvtrinh

Retired high school math teacher.
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