Mathematics
A student has taken 5 quizzes with a mean score of 78. After a sixth quiz, the mean score for all 6 quizzes is 80. What score did the student earn on the sixth quiz?
- A80
- B88
- C82
- D90
Not A. 80 incorrectly assumes the sixth score equals the new mean, ignoring the extra points needed to raise the earlier average of 78.
D is right. The first five quizzes total 390, and all six must total 480, so the sixth score is 90. The choice 82 comes from adding the 2-point mean increase to the new mean, but it does not account for the total needed across all six quizzes.