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by sivaelectric » Tue May 31, 2011 2:55 am
What number is 30% of a?

1. 20% of a is 100
2. 300 is of a
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Source: — Data Sufficiency |

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by Anurag@Gurome » Tue May 31, 2011 3:19 am
sivaelectric wrote:What number is 30% of a?

1. 20% of a is 100
2. 300 is of a
(1) 0.20 * a = 100 implies a = 500
So, the number = 0.30 * 500 = 150; SUFFICIENT.

(2) 300 is of a some number seems to be missing!
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by sivaelectric » Tue May 31, 2011 3:23 am
Anurag@Gurome wrote:
sivaelectric wrote:What number is 30% of a?

1. 20% of a is 100
2. 300 is of a
(1) 0.20 * a = 100 implies a = 500
So, the number = 0.30 * 500 = 150; SUFFICIENT.

(2) 300 is of a some number seems to be missing!
Anurag sir,
[spoiler]300 is of a is nothing but 300 = a. so we can get the answer from second choice also. so the answer is D[/spoiler]
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by Anurag@Gurome » Tue May 31, 2011 3:28 am
sivaelectric wrote:
Anurag sir,
[spoiler]300 is of a is nothing but 300 = a. so we can get the answer from second choice also. so the answer is D[/spoiler]
Ok. But then the required answer will be different from both the statements, which should not be the case.
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by sivaelectric » Tue May 31, 2011 3:32 am
Sir,
I dont think so. I think you don't need to solve a data sufficiency question. You just need to check whether the given information is suitable to solve the data. Is it not.:)
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by Anurag@Gurome » Tue May 31, 2011 3:36 am
sivaelectric wrote:Sir,
I dont think so. I think you don't need to solve a data sufficiency question. You just need to check whether the given information is suitable to solve the data. Is it not.:)
Absolutely, I agree with you Siva that we need not solve the DS questions for an answer :)
But still, in a good DS question, both the statements should give the same answer, even though we need not solve the statements.
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by sivaelectric » Tue May 31, 2011 3:39 am
I just checked out again with the material which I am using and it is mentioned that you dont have to get the same answer and you just need to find whether the given is suitable to solve the question or not. :(
Last edited by sivaelectric on Tue May 31, 2011 3:50 am, edited 3 times in total.
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by Anurag@Gurome » Tue May 31, 2011 3:42 am
sivaelectric wrote:I just checked out again with the material which I am using and it is mentioned that you dont have to get the same answer and you just need to find whether the given is suitable to solve the question or not. :(
I cannot comment on this Siva.
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by sanju09 » Wed Jun 01, 2011 4:36 am
sivaelectric wrote:I just checked out again with the material which I am using and it is mentioned that you dont have to get the same answer and you just need to find whether the given is suitable to solve the question or not. :(
Received a PM to answer this thread...

If this is the case Siva then I am sorry to say that you are not using a genuine GMAT material, and it is highly possible now that the questions from that material could lead you to many more such mistaken beliefs about GMAT.

Remember, in a genuine GMAT DS question, although we aren't supposed to find the answer till end, but even then if the two statements are separately worked out, then even if it separately cannot provide you the answer but still it would never ever contradict each other in any manner. For me the wordings of this DS is ambiguous and do not portray GMAT DS.
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by sivaelectric » Wed Jun 01, 2011 4:48 am
Sanju but that specific material which I referred is a big player in the GMAT prep. So there is no way you can doubt the ingenuity. :) I dont want to mention the name here.
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by David@VeritasPrep » Wed Jun 01, 2011 5:05 am
I was asked to comment on this one.

Siva -

Please do not doubt Anurag when he says that the two statements must give you the same answer. This is an extremely important principle of data sufficiency. It is a way for you to check yourself to make sure that you do not THINK that something is sufficient when YOU have forgotten something (for example you have forgotten to check zero or a fraction or a negative number).

Let's look at the following simplified question:

X = ?

1) 2x = 10

2) 3x = 21

In this case this would not be a viable question. This is because the two statements must give you the same result.

Actually GMAT questions never make this error. Sometimes questions that are written by others can make this simple error. If it is the case that this is a Veritas question and if it has been written correctly here then we may have made such an error. You can be assured that we will look into it.

The main point is that on the GMAT the two statements will always ALLOW FOR THE SAME RESULT. Meaning that there will be a way for both statements to be true at the same time.

It is true that you do not have to solve on data sufficiency - but sometimes it helps to be able to check your answers. I am writing an article on this very topic that will be posted within the next few days so look for that!
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by sivaelectric » Wed Jun 01, 2011 5:47 am
David thanks for the explanation :) :)
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by David@VeritasPrep » Wed Jun 01, 2011 6:51 am
Thanks for pointing it out -- we will check that and if there is a flaw we will certainly correct it.

And I will let you know when the article is up -- it should be called something like "The Usual Suspects in Data Sufficiency"
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by sivaelectric » Wed Jun 01, 2011 6:54 am
That would be great David and BTW I took the question from your app for iPhone. :) waiting for your article
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by Ian Stewart » Fri Jun 03, 2011 9:26 pm
sivaelectric wrote:What number is 30% of a?

1. 20% of a is 100
2. 300 is of a
The second statement above is clearly incomplete. The issue with the question is not that the statements are contradictory; the problem is that the sentence "300 is of a" is completely meaningless. It does not mean that 300 is equal to a, as you seem to have interpreted it. I don't know whether the error exists in the original source material, but there are clearly words missing; I imagine it is supposed to read "300 is 60% of a" or something similar.
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