Question

The average marks of boys in a class is 52 and that of girls is 42. The average marks of boys and girls combined is 50. The percentage of boys in the class is

Answer 1

Let the number of boys and girls be xx and yy∴52x+42y=50(x+y)∴52x+42y=50(x+y)52x+42y=50x+50y52x+42y=50x+50y52x−50x=50y−42y52x−50x=50y−42y2x=8y2x=8yx=4yx=4yTotal number of students in the class = x+yx+y=4y+y=4y+y=5y=5yPercentage of boys = 4/y/5/y×/10020