Bunuel wrote:

TomB wrote:

Is the number of members of Club X greater than the number of members of Club Y ?

(1)Of the members of Club X, 20 percent are also members of Club Y.

(2)Of the members of Club Y, 30 percent are also members of Club X.

can we use matrix approach for this question. every body is saying:

0.20x=0.30y

x/y=3/2 so x>y.

what i know is ratios are not enough to compare two quantities. I am very bad at Ratio and proportions. Please explain

Is the number of members of Club X greater than the number of members of Club Y?(1) Of the members of Club X, 20 percent are also members of Club Y --> 20% of X are members of both X and Y --> 0.2X={both}. Not sufficient.

(2) Of the members of Club Y, 30 percent are also members of Club X --> 30% of Y are members of both X and Y --> 0.3Y={both}. Not sufficient.

(1)+(2) 0.2X={both}=0.3Y --> X/Y=3/2 --> X>Y. Sufficient.

Answer: C.

TomB wrote:

0.20x=0.30y

x/y=3/2 so x>y.

what i know is ratios are not enough to compare two quantities. I am very bad at Ratio and proportions. Please explain

If x and y are both negative then x<y, for example: x=-3<-2=y and if x and y are both positive then x>y. So generally you are right x/y=3/2 is NOT enough to say whether x>y. Though in our case since x and y represent # of people then we know that they must be

positive integers, so case 1 is ruled out and we CAN say that x>y.

Hope it's clear.

Hi

Can I solve this kind of question by assuming total numbers??

for example while combining 1 and 2:

I assumed 100 total members then assumed two scenarios :

1: X group: 30 members: 20% in Y , 51 in X

2 Y group: 70 : 70+6 = 76 30% IN X

The same way vice versa situation where X is 70 and Y is 30:

By doing this way I got E....

cAN you pls explain why my approach is wrong???