Multiple choice

In a class of 40 students, 60% are girls. The average of the girls' marks is 72 and that of the boys' marks is 54. What are the average marks of the whole class?

  1. 65.4

  2. 65.0

  3. 64.8

  4. 65.2
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C Correct answer
Explanation

Girls = 0.6 * 40 = 24. Boys = 16. Total marks = (24 * 72) + (16 * 54) = 1728 + 864 = 2592. Average = 2592 / 40 = 64.8.

AI explanation

Out of 40 students, 60 percent are girls, which means there are 24 girls and 16 boys. The total marks of the girls is 24 multiplied by 72, which equals 1728. The total marks of the boys is 16 multiplied by 54, which equals 864. The overall average marks of the class is the total sum, 1728 plus 864, divided by 40 students. The result is 64.8 marks.

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