what is this problem?

Question

there are 2 boys for every 5 girls. there are 21 students. how many are boys?
i need to set up a proportion. i cant seem to understand it. i can do other ones but im stumped on this one. help

Answer 1

The ratio is 5 / 2

5 + 2 = 7

5/7 = the amount of girls

2 / 7 = the amount of boys

21 = The total amount of girls and boys

- - - - -

5 / 7(21) =

105 / 7 =

15. . .girls

- - - - -

2 / 7 (21) =

42 / 7 =

6 . . .Boys

- - - -

There are 15 girls and 6 boys

- - - - - - -s-

Answer 2

the boy to girl ratio is 2:5.

So,

boys = 2x and girls = 5x

Therefore 2x + 5x = 21

7x = 21

x = 3.

Plug in x.

So, boys = 2(3) = 6 and girls = 5(3) = 15

6 + 15 = 21.

Answer 3

there are two boys for every five girls: therefore the ratio of boys to girls is 2:5

therefore if you have 21 students, then you know that in every 7 students 2 will be boys (because ration is 2:5 i.e. 2/7 boys, 5/7 girls) so:

number of boys = 21 x (2/7) = 6 boys

Answer 4

let b be the number of boys
21 - b is the number of girls.

for every 5 girls, there are 2boys

the ratio is 5/2

5/2 = (21-b) / b

42 - 2b = 5b

42 = 7b
b = 6


the numbesr are small, you can solve this by counting
2 boys , 5 girls ( 7 total)
4 boys, 10 girls (14 total)
6boys, 15 girls (21 total)

so the answer is 6 boys and 15 girls

Answer 5

6 boys

Answer 6

The proportion would be:
2 (boys)/ 7 (boys+girls) = x (boys) / 21 (boys+girls)
x=6, so
There are six boys. (15 girls)

Answer 7

B=Boy
Count the B's

1-B
2-B
4-G
3-G
5-G
6-B
7-B
8-G
10-G
11-G
12-B
13-B
14-G
15-G
16-G
17-B
18-B
19-G
20-G
21-G
If you are over the age of 8, you got's a problem.
Better stay off the computer and study.

Answer 8

6 boys 15 girls

(2x3) and (5x3)