Question

in a class the average scorr of girls in a examination is 80 and that of boys is 70 . the average score of the whole class is 74 . find the ratio of girls and boys in the class​

Answer 1

Answer:

Ratio of girls and boys is 3:2

Step-by-step explanation:

Girls average marks of x students =80

Boys average marks of y students =70

Average of whole class is 74 i,e

$74=\frac{80\times x+70 \times y}{x+y} \\74x+74y-80x-70y=0\\4y=6x\\\frac{y}{x} =\frac{6}{4} \\\frac{y}{x} =\frac{3}{2}$

Ratio of girls and boys is 3:2

Answer 2

Step-by-step explanation:

Girls averagecmarks of x students = 80

Boys average Mark's of y students = 70

Average of whole class is 74

74 = 80×x+70×y /x+y

74x+74y = 80x-70y

4y = 6x

y/x = 6/4

y/x=3/2

3:2