Question

rest? 6. The average score of a class of boys and girls in an examination is x. The ratio of boys and girls in the class is 3:1. If the average score of boys is x +1, find the average score of girls​

Answer 1

Step-by-step explanation:

rest? 6. The average score of a class of boys and girls in an examination is x. The ratio of boys and girls in the class is 3:1. If the average score of boys is x +1, find the average score of girls

Answer 2

The average score if girls is (x-3)

let no of boys in class = b

and no of girls = g

now, given b/g=3/1 => b=3g -----(1)

Again, let sum of scores of boys= P

and sum if scores of girls = Q

now, average score of whole class =x

so,

we can say that

P+Q/(g+b) =x {putting value of b from (1) }

P+Q =x(g+3g)

P+Q=4gx -------(2)

also, given that

average score if boys = x+1

so,

P/b =x+1 {putting values from(1)}

P/3g=x+1

P= 3g(x+1) ---------(3)

putting value of P from (3) to (2)

3g(x+1) + Q = 4gx

Q = 4gx - 3g(x+1)

Q = g(4x - 3x - 3)

Q/g = x-3 -----(4)

Now, average score of girls = Q/g

which according to (4) had the value of (x-3)

hence, the answer is derived which is x-3