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Is the number of members of Club X greater than the number [#permalink]
14 Aug 2012, 02:41

2

This post received KUDOS

Using the table it can also be solved easily. As the individual entries result in insufficient data, options A/B/D can be eliminated. Combining both the entries we can observe under the column "members of X and members of Y" ,the value of .2X=.3Y, which answers X>Y .Hence C is the ans.

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Whatever one does in life is a repetition of what one has done several times in one's life! If my post was worth it, then i deserve kudos

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.

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.

Re: Is the number of members of club X greater than the number o [#permalink]
08 May 2012, 05:35

1

This post received KUDOS

From what I can deduce, we can make a table for the two possibilities (table formatting is a mess, sorry) :

...................|.Club Y..........NOT Club Y | Club X...........|....? ..............................| X NOT Club X.....|.....................................| .......................Y Let X be the number of members in club X and let Y be the number of members in club Y. Question stem asks whether X>Y?

1. Top left corner contains info about number common number of members in both clubs. Thus, ? = .2 X But we can't decide whether X>Y. NOT SUFFICIENT.

2. Top left corner contains info about number common number of members in both clubs. Thus, ? = .3 Y But we can't decide whether X>Y. NOT SUFFICIENT.

Combine the two, ? = .2X = .3 Y. Since number of members is a positive integer, we know the answer to X>Y. SUFFICIENT.

Is the number of members of Club X greater than the number of me [#permalink]
15 Jun 2013, 09:47

1

This post received KUDOS

clearly A or B were insufficient.

my process : Total members = Members of X only (Say A) + Members of Y Only (Say B) + Members of Both = A + B + both Now from the statements both= either 0.2A or 0.3B Total = A + B + 0.2A or = A + B + 0.3B Equating both A + B + 0.2A= A + B +0.3B 0.2A=0.3B A=1.5B => X>Y Answer C

Re: Is the number of members of Club X greater than the number [#permalink]
30 Jul 2014, 08:03

1

This post received KUDOS

Expert's post

GGMAT760 wrote:

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.

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???

Your approach does not make much sense. The statements give certain relationship between the numbers in X and Y, you cannot assume arbitrary values for them.

Also, if there are 30 members in X, then 20% of them, so 6 members, are also in Y. Now, we also know that these 6 members comprise 30% of Y, so 0.3Y=6 --> Y=20 --> X=30 > Y=20. _________________

Re: Is the number of members of Club X greater than the number o [#permalink]
03 Dec 2013, 21:31

nanz236 wrote:

clearly A or B were insufficient.

my process : Total members = Members of X only (Say A) + Members of Y Only (Say B) + Members of Both = A + B + both Now from the statements both= either 0.2A or 0.3B Total = A + B + 0.2A or = A + B + 0.3B Equating both A + B + 0.2A= A + B +0.3B 0.2A=0.3B A=1.5B => X>Y Answer C

yes, i agree with your approach. It was very hard for me to understand how can we equate 0.2x = 0.3y. I do not seem to get the correlation between these 2 statements to equate 0.2Y = 0.3 Y.

Re: Is the number of members of Club X greater than the number [#permalink]
02 Jul 2014, 14:44

I got this question wrong because I didn't think to set the x and y statements against each other, because in my mind I just pictured .2x and .3y as different figures. After I reviewed the problem I pictured it this way and it became clear (I'm not using the numbers from the problem):

Group X: Group Y:

So what makes up group x's overlap?

What makes up group y's overlap?

In my example 80% of group X is in group y, and 66.6% of group y is in group b, but the actual count is the exact same for both so you can set them against each other.

Re: Is the number of members of Club X greater than the number [#permalink]
30 Jul 2014, 07:07

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.

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???

Re: Is the number of members of Club X greater than the number [#permalink]
21 Jan 2015, 06:27

This question was frustrating to me. My answer is E because there was no mention of the amount of people in each club for instance: club A has 10 people, club B has 20 people

Overlap= 6B+2A

Club A then has 8 members Club B has 14 members or if the numbers are different then Club A could have more leading to both being insufficient.

Is the assumption that there are both the same number of people in each club to start or is this a flaw??

Re: Is the number of members of Club X greater than the number [#permalink]
21 Jan 2015, 07:55

Expert's post

CMAC5 wrote:

This question was frustrating to me. My answer is E because there was no mention of the amount of people in each club for instance: club A has 10 people, club B has 20 people

Overlap= 6B+2A

Club A then has 8 members Club B has 14 members or if the numbers are different then Club A could have more leading to both being insufficient.

Is the assumption that there are both the same number of people in each club to start or is this a flaw??

We are asked whether the number of members of Club X is greater than the number of members of Club Y. How can we assume that there are equal number of people in X and Y?

Re: Is the number of members of Club X greater than the number [#permalink]
21 Jan 2015, 13:12

Expert's post

Hi All,

This DS question can be solved by TESTing VALUES.

We're asked if the number of members of Club X is greater than the number of members of Club Y? This is a YES/NO question. In these sorts of situations, it's common for some members to belong to BOTH Clubs, so we have to keep careful track of the numbers and possibilities....

Fact 1: 20% of the members of Club X are ALSO members of Club Y

IF... Club X has 100 members, then 20 of those members ALSO belong to Club Y. IF Club Y has 0 unique members, then the answer to the question is YES. IF Club Y as 1,000 unique members, then the answer to the question is NO. Fact 1 is INSUFFICIENT

Fact 2: 30% of the members of Club Y are ALSO members of Club X

This Fact offers the same general logic as Fact 1 (above). Without knowing the number of unique members in Club X, the answer to the question could be either YES or NO. Fact 2 is INSUFFICIENT

Combined, we know... 20% of the members of Club X are ALSO members of Club Y 30% of the members of Club Y are ALSO members of Club X These specific members are the SAME PEOPLE...

This means that .2(X) = .3(Y)

2X = 3Y X = (3/2)(Y)

This means that X MUST be greater than Y, so the answer to the question is ALWAYS YES. Combined, SUFFICIENT

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