Question

the avarage score of 132 students in a test is 98.the ratio of the number of boys to that of girls is 5:6 .the avarage score of the boys is 25% more than that of the girls.the avarage score of the boys is​

Answer 1

Answer:

let the number of boys = x

number of girls = y

we need to find \frac{x}{y}

y

x

.

The average score of boys in the examination is 71

total score of boys = 71 × x = 71x

The average score of girls in the examination is 73

total score of girls = 73 × y = 73y

So total mark of school = 71x + 73y ---------------(1)

average score if school in examination 71.8

so total mark = 71.8 × (x+y) -----------------(2)

From equations (1) and (2);

71x + 73y = 71.8(x+y)

⇒ 71x + 73y = 71.8x + 71.8y

⇒ 73y - 71.8y = 71.8x - 71x

⇒ 1.2y = 0.8x

⇒0.8x = 1.2y

⇒\frac{x}{y} = \frac{1.2}{0.8}= \frac{3}{2} =\boxed{3:2}

y

x

=

0.8

1.2

=

2

3

=

3:2

Ratio of boys and girls is 3:2.