Multiple choice

The average score obtained by 120 candidates was 35. If the average score of passed candidates was 39 and that of failed candidates was 15, then the number of candidates who passed the examination was

  1. 100

  2. 90

  3. 95

  4. 105

  5. 110
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A Correct answer
Explanation

Let p be the number of passed candidates. 39p + 15(120-p) = 35 * 120. 39p + 1800 - 15p = 4200. 24p = 2400. p = 100.

AI explanation

The total score of all 120 candidates is 120 times 35, which equals 4200. Let the number of passed candidates be x, making the number of failed candidates 120 minus x. The equation for total scores becomes 39x plus 15(120 minus x) equals 4200. Solving 39x plus 1800 minus 15x equals 4200 yields 24x equals 2400, so x equals 100.

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