Question
the ratio of the number of boys to the number of girls in a class is 4:7. if there are 12 more girls than boys, find the total number of pupils in the class.
Answers
Sarah
Wendy went to a bakery to buy cakes and doughnuts. She spent $14 altogether on 30 cakes and doughnuts. Each cake cost 40 cents and each doughnut cost 50 cents. How many cakes and doughnuts did she buy?
Bosnian
b = the number of boys
g = the number of girls
b / g = 4 / 7 Multiply both sides by 7
7 b / g = 4 Multiply both sides by g
7 b = 4 g Divide both sides by 4
7 b / 4 = g
g = 7 b / 4
g = 12 + b
7 b / 4 = 12 + b Subtract b to both sides
7 b / 4 - b = 12 + b - b
7 b / 4 - b = 12
7 b / 4 - 4 b / 4 = 12
3 b / 4 = 12 Multiply both sides by 4
3 b = 48 Divide both sides by 3
b = 48 / 3 = 16
g = b + 12 = 16 + 12 = 28
16 boys and 28 girls
The total number of pupils in the class = b + g = 16 + 28 = 44
Proof :
b / g = 16 / 28 = 4 * 4 / ( 4 * 7 ) = 4 / 7
g = b + 12
g = 16 + 12 = 28
g = the number of girls
b / g = 4 / 7 Multiply both sides by 7
7 b / g = 4 Multiply both sides by g
7 b = 4 g Divide both sides by 4
7 b / 4 = g
g = 7 b / 4
g = 12 + b
7 b / 4 = 12 + b Subtract b to both sides
7 b / 4 - b = 12 + b - b
7 b / 4 - b = 12
7 b / 4 - 4 b / 4 = 12
3 b / 4 = 12 Multiply both sides by 4
3 b = 48 Divide both sides by 3
b = 48 / 3 = 16
g = b + 12 = 16 + 12 = 28
16 boys and 28 girls
The total number of pupils in the class = b + g = 16 + 28 = 44
Proof :
b / g = 16 / 28 = 4 * 4 / ( 4 * 7 ) = 4 / 7
g = b + 12
g = 16 + 12 = 28