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
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?
2 answers
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
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