Multiple choice

In an examination, the average was found to be 60 marks. Due to some error, marks of the 100 candidates had to be changed from 110 to 70 each and average came down to 40 marks. Total number of candidates who took the examination were

  1. 200

  2. 300

  3. 400

  4. 600

  5. None of these
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A Correct answer
Explanation

Let N be the number of candidates. Initial sum = 60N. Change = 100 * (70 - 110) = -4000. New sum = 60N - 4000. New average = 40 = (60N - 4000) / N. 40N = 60N - 4000. 20N = 4000. N = 200.

AI explanation

Let the total number of candidates be N. The total reduction in marks is 100 candidates multiplied by a 40-mark decrease each, which equals 4000. This reduction caused the average to drop by 20 marks, from 60 to 40. Setting up the equation 20 times N equals 4000 gives N equal to 200 total candidates.

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