Find the ratio of the number of boys to the number of girls

1. Oct 22, 2004

dibilo

my 12 year old bro brought this question to mi and i was dumbfounded...feel so stupid by logic i know its 2:1 . but i cant explain ..maybe u guys can have a go.

Class A and Class B have the same number of pupils. The ratio of the number of boys in Class A to the number of boys in Class B is 3:2. The ratio of the number of girls in Class A to the number of girls in Class B is 3:5. Find the ratio of the number of boys to the number of girls in Class A. :rofl: :rofl:

Last edited: Oct 22, 2004
2. Oct 23, 2004

TenaliRaman

xA = number of boys in class A
yA = number of girls in class A
xB = number of boys in class B
yB = number of girls in class B

given,
xA + yA = xB + yB
xA/xB = 3/2
yA/yB = 3/5

find xA/yA?

-- AI

3. Oct 23, 2004

GCT

A very simple way to do this is to simply place an arbitrary value (for instance, 10) for a specific variable and go on from there.......plugging in.

4. Oct 26, 2004

regor60

boys to girls

b1+g1=b2+g2
b1/b2=3/2
g1/g2=3/5

b1/g1+g1/g1=b2/g1+g2/g1
b1/g1=b2/g1+2/3
b2/g1=b2/b1 * b1/g1

so b1/g1= (2/3)(b1/g1) +2/3

finally b1/g1 =2

5. Oct 27, 2004

Noticibly F.A.T

i got 5:6 but i am an idiot