The ratio of the number of girls to the number of boys in a sports club is 3:6. There are 15 more boys than girls in the club. How many pupils are in the club altogether?

Answer 1

girls : boys = 3:6 = 1:2

let the number of girls be x
let the number of boys be 2x

2x - x = 15
x = 15

we have 15 girls and 30 girls for a total of 45 pupils

Answer 2

g = numbers of girls

b = number of boys

There are 15 more boys than girls mean:

b = g + 15

The ratio of the number of girls to the number of boys in a sports club is 3:6 mean:

g / b = 3 / 6

3 / 6 = 1 / 2 so:

g / b = 1 / 2

Replace b = g + 15 in this equation.

g / ( g + 15 ) = 1 / 2 Multiply both sides by 2

2 g / ( g + 15 ) = 1 Multiply both sides by g + 15

2 g = g + 15 Subtract g to both sides

2 g - g = g + 15 - g

g = 15

b = g + 15 = 15 + 15 = 30

In the club are altogether b + g pupils.

b + g = 30 + 15 = 45 pupils