The girl:boy ratio in class A was 1:3 and the same ratio in Class B was 2:1. When the two classes were combined, the ratio became 1:1. If class A had 24 girls,Find
a) Total Boys in class A
b) Total Boys: Class B
c) Total Girls Class B:
d) Ratio of Total students in Class A : Class B
The question is edited version of this
https://gmatclub.com/forum/the-girl-boy ... 51406.htmlHey in this question i know how to solve it now, but why cant we take values for this like if I multiply ratio:
Class A, Girls and Boys: 1:3, if i multiply it by 100, it will become 100: 300, Total: 400 and
For Class B, Girls and Boys: 2:1, if i multiply it by 100, it will become: 200: 100, Total: 300
a) Now ratio of Girls in both class A and B to that of boys becomes: 300: 400 Edit: I did wrong calculation here, thats why ans came wrong: i took boys total as 300 when it is actually 400, i.e 1:1 equation is not satisfied, we need to take different values: to make it 1:1
Class A: 1:3 = 4
Class B 2:1 = 3
LCM is 12, so make either one multiply to get multiple of 12, and other one need to think of number so ratio would be 1:1
Class A: 1:3 = total; 4, multiplying by 3 = 3:9
Class B: 2:1 = total: 3, Multiplying by 6 = 12: 6 ( this step is bit difficult though to figure out what number would make ratio 1:1 on adding ). If we multiply by 4 we wont get ratio of boys and girls as 1: 1 so need to think of next value..
Ratio: Boys and Girls is now: 15: 15 combined and Ratio of Class A to Class B is 3+9 : 12+6 = 12:18 = 2:3 or 3:2
https://gmatclub.com/forum/allegation-s ... l#p2357742MentorTutoring has explained this very nicely here..
Ans)
a)72 , b) 48, c) 96 d) Ratio: 2:3
b)72 , b) 48, c) 96 d) Ratio: 4:3