Question
In a school, the average number of books that some
numbers of boys have is 100 and average number of books that some numbers of girls have is 70. If each boy have 5 books then the average numbers of books with all the students become 80. The total number of boys is what percentage of the total number of students in that school?Solution
Let the total number of boys be x. and the total number of girls be y. The total number of books boys have = 100x The total number of books the girls have = 70y If each of the boy have 5 books, then the remaining number of books = 100x – 5x = 95x The sum of the all the books = 80(x + y) = 95x + 70y 10y = 15x x : y = 2 : 3 Required % = (2/5) × 100 = 40%
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