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GATE 2025 CS (CS1) – Question 3

General Aptitude · Quantitative Aptitude: Arithmetic and Number Computation · 1 mark · Multiple choice

The average marks obtained by a class in an examination were calculated as 30.8. However, while checking the marks entered, the teacher found that the marks of one student were entered incorrectly as 24 instead of 42. After correcting the marks, the average becomes 31.4. How many students does the class have?

  1. 25
  2. 28
  3. 30
  4. 32

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Correct answer: (C) 30

Explanation

The total rises by 42-24=18, and the average rises by 0.6. So n = 18/0.6 = 30.