Question
In a class, the ratio of boys to girls is 7:5. If 21
boys and 9 girls join the class, the ratio becomes 3:2. Find the original number of students.Solution
ATQ, Let boys = 7x, girls = 5x New ratio: (7x+21)/(5x+9) = 3/2 2(7x+21) = 3(5x+9) 14x + 42 = 15x + 27 x = 15 Original students = 7x + 5x = 12x = 12*15 = 180 Answer: 180
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