Question

copper is there in the alloy?
The ratio of the girls to boys in a class is 3 : 5. What percentage of the number are
boys?​

Answer 1

Step-by-step explanation:

Lets say there are 100 students in the class

The boys and girls are in the ratio 3:2=3x:2x with unknown multiplier of

′

x

′

Total number of student is 3x+2x=100

so 5x=100

x=20

Number of boys in the class =3x=60

Number of girls in the class =2x=40

Number of boys who are adults = 20% of number of boys =

100

20

×60=12

Number of girls who are adults = 25% of number of girls =

100

25

×40=10

Total number of boys and girls who are adults =12+10=22

Total number of boys and girls who are not adults = 100−22=78

Percentage of boys and girls who are not adults =

100

78

×100=78%.

so option C is correct.

Answer 2

Step-by-step explanation:

let the ratios be 3x and 5x.

A/q to the question

percentage of students=100

so

3x+5x/5 = 100

8x/5=100

8x=500

x=500/8

x=62.5%