In a class of 100 students there are 70 boys whose average marks is 75. If the average marks of the whole class is 72, then what is the average marks of the girls?
Question
In a class of 100 students there are 70 boys whose average marks is 75. If the average marks of the whole class is 72, then what is the average marks of the girls?
Solution
Sure, here is the step by step solution:
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First, we know that the average marks of the whole class is 72. This means that the total marks of all the students in the class is 72 * 100 = 7200.
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We also know that there are 70 boys in the class and their average mark is 75. This means that the total marks of all the boys is 70 * 75 = 5250.
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To find the total marks of all the girls, we subtract the total marks of the boys from the total marks of the class. So, 7200 - 5250 = 1950.
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The number of girls in the class is the total number of students minus the number of boys. So, 100 - 70 = 30 girls.
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Finally, to find the average marks of the girls, we divide the total marks of the girls by the number of girls. So, 1950 / 30 = 65.
Therefore, the average marks of the girls in the class is 65.
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