Multiple choice

In a town, there were 35 students who took part in a quiz. The overall average score of these students was 76. Later, it was discovered that the average score of the first 18 students was 72.6, while the average score of the last 18 students was 77.4. When the score of the 18th student was excluded from the calculation, what was the new average score of the remaining students?

  1. 72.24

  2. 75.04

  3. 76.06

  4. 77.06
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D Correct answer
Explanation

The total score of all 35 students is 35 * 76 = 2,660. The sum of the first 18 and last 18 students' scores is (18 * 72.6) + (18 * 77.4) = 1,306.8 + 1,393.2 = 2,700. Since the 18th student is included in both groups, their score is 2,700 - 2,660 = 40. Excluding this student leaves a total score of 2,620 for the remaining 34 students, resulting in a new average of 2,620 / 34 = 77.06.

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