Question

2/3 of a class are girls. What is the ratio girls to boys in the class? What is the ratio boys to girls in the class?​

Answer 1

If a class has 2/3 girls.

Lets ask ourselves, what does this mean?

It means that 2/3 of the class are girls and therefore 1/3 of the class are boys. I.e. for every 2 girls in the class there is 1 boy in the class.

Therefore the ratio of girls to boys is

2 : 1

Answer 2

Since 2/3 are girls the other 1/3 would have to be boys to complete the fraction.