Question
The ratio of number of boys to number of girls in a
class is 2:3, respectively. The average marks of all the boys is (x − 4) and the average marks of all the students in the class is (x + 2). Find the average marks of all the girls in the class.Solution
Let the number of boys and number of girls be '2a' and '3a', respectively.
Total marks of the class = 5a × (x + 2) = 5ax + 10a
Total marks of all boys = 2a × (x − 4) = 2ax − 8a
So, total marks of all girls = (5ax + 10a) − (2ax − 8a) = 3ax + 18a
Therefore, average marks of girls = (3ax + 18a) / 3a = (x + 6)
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