Answers

  • Brainly User
2015-11-16T07:27:15+08:00
There were total of 6 quizzes.  Divide the quizzes to 3; the first 3 quizzes and the last 3 quizzes.
6 ÷ 3 = 2 averages

x = average for the first three quizzes
83 = average for the last three quizzes
86 - overall average for the 2 sets of quizzes (first 3 quizzes and last three quizzes)

Equation:
x + 83  = 86
   2

x + 83 = 86 (2)
x + 83 = 172
x = 172 - 83
x = 89 

The average for the first three quizzes is 89.
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