Multiple choice

The average marks of a class of 40 students were 85. Later on, it was found that the marks of a student were wrongly printed as 90, instead of 95. Find the correct average marks of the class.

  1. 86.012

  2. 85.883

  3. 85.125

  4. 84.223

  5. 85.661
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C Correct answer
Explanation

Total marks = 40 * 85 = 3400. Correct total = 3400 - 90 + 95 = 3405. Correct average = 3405 / 40 = 85.125.

AI explanation

The correct average is found by dividing the correction amount by the total number of students, then adding it to the initial average. The marks increase by 95 minus 90, giving a total increase of 5. Dividing this 5 by 40 yields 0.125. Adding this 0.125 to the initial average of 85 results in the correct average of 85.125.

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