Multiple choice

In an exam, the average was found to be 60 marks. After deducting an error, the marks of 80 students were found to have changed from 90 marks to 60 marks each. The average has also come down to 50 marks. Determine how many students have taken the exam?

  1. 360

  2. 240

  3. 120

  4. 250

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let n be total students. Initial total marks = 60n. After error correction, 80 students' marks changed from 90 to 60, meaning each lost 30 marks. Total marks deducted = 80 × 30 = 2400. New total = 60n - 2400 = 50n. Solving: 10n = 2400, so n = 240 students.

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