Multiple choice

A class of 20 students has an average test score of k points. One student, who had scored 55, leaves the class and is replaced by a student who scored 75. In terms of k, what is the new average score for the 20 students?

  1. k + 7 5

  2. k - 7 5

  3. k + 1

  4. 20k + 28

  5. k - 1
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total score = 20k. New total = 20k - 55 + 75 = 20k + 20. New average = (20k + 20) / 20 = k + 1.

AI explanation

The total score for the class originally is 20k points. When a student scoring 55 is replaced by a student scoring 75, the class total increases by 20 points, making the new total 20k plus 20. Dividing this new total by the 20 students gives the new average, which simplifies to k plus 1.

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