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.

Answer 1

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?

Answer 2

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