In one classroom the girl to boy ratio is7to 6. There are 78 children in total. How many boys are there ?

Question

need to set up a ratio? 

Answer 1

Set up a proportion for boys over total:

 

Boys              6          b

------     --->   ---  =   ----

Total             13        78

 

Then cross multiply to get 13b = 6(78)

 

Solve for b to get the number of boys. 

Answer 2

Girls & Boys ratio= 7/6

let total # of Girls = 7x,    total # of Boys = 6x

7x+6x=78

13x=78

x=6

 # of Girls = 42, # of Boys = 36