Multiple choice

The average marks of a class of 50 students were calculated to be 64.15. It was later discovered that the marks of a student were taken to be 39, instead of 75. Find the real average of the class.

  1. 64.87

  2. 65.07

  3. 64.89

  4. 64.99

  5. 64.97
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A Correct answer
Explanation

 By taking 75 instead of 39, total increment is 36. These 36 marks are equally distributed in all 50 students. Hence. marks of each student are increased by 0.72. Hence, average becomes 64.15 + 0.72 = 64.87.

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