Multiple choice

A classroom has a total of 120 students. They appear in an examination and get an average of 65 marks. The students who have passed the examination have an average of 74 marks, while the failed students have an average of 20 marks. The number of failed students is

  1. 20

  2. 16

  3. 18

  4. 14

  5. 22
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A Correct answer
Explanation

Let x be the number of failed students. Then 120-x is the number of passed students. Total marks = 120 * 65 = 7800. Passed marks = (120-x) * 74. Failed marks = x * 20. (120-x)*74 + 20x = 7800. 8880 - 74x + 20x = 7800. 54x = 1080. x = 20.

AI explanation

The total marks of all 120 students is 120 multiplied by 65, or 7800. Let the number of failed students be y, so the number of passed students is 120 minus y. The equation for total marks becomes 20y plus 74 times (120 minus y) equals 7800, which simplifies to 8880 minus 54y equals 7800. Solving for y gives 54y equals 1080, meaning y is 20.

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