Multiple choice

In a class test, in mathematics, $10$ students scored $75$ marks, $12$ students scored $60$ marks, $8$ scored $40$ marks and $3$ scored $30$ marks. The mean of their score is (approximately) _________.

  1. $57$ marks
  2. $56$ marks
  3. $15$ marks
  4. $54$ marks
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A Correct answer
Explanation

The mean is calculated by finding the total sum of marks and dividing by the total number of students. Total marks = (10*75) + (12*60) + (8*40) + (3*30) = 750 + 720 + 320 + 90 = 1880. Total students = 10 + 12 + 8 + 3 = 33. Mean = 1880 / 33 = 56.96, which is approximately 57.

AI explanation

Using the direct method for the arithmetic mean, we multiply each score by its frequency to find the total marks. The sum of the products is (10 * 75) + (12 * 60) + (8 * 40) + (3 * 30) = 750 + 720 + 320 + 90 = 1880. The total number of students is 10 + 12 + 8 + 3 = 33. Dividing the total marks by the total students gives 1880 / 33, which is approximately 57 marks.

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