Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 18 Jun 2012
Posts: 31

Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
15 Jul 2012, 21:01
Hi I might be asking a stupid question but then i couldn't stop myself from asking it. Suppose a DS question asks you to find an answer. Lets assume they ask you to find the median of a certain data set with variables in it. based on the two options you have to determine if median >= 5 or not ? If both the option of the question are able to solve it, is it necessary that both questions should get you the same result ? For ex if option A gets the result as median = 5 is it necessary that if option B also is able to get the right answer then it should also get the median value as 5 ?? can there be a possibility that option B gets an answer different than 5 ? Thanks smartmanav Ask a question be a fool for 3 minutes, don't ask n b a fool all your life !!



GMAT Tutor
Status: Tutor  BrushMyQuant
Joined: 05 Apr 2011
Posts: 622
Location: India
Concentration: Finance, Marketing
GPA: 3
WE: Information Technology (Computer Software)

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
16 Jul 2012, 04:16
Hi, As far as I think GMAT "might" not give you any such question inw hich both Stat1 and Sta2 are giving you different answers individually. If i get a question like this then i will still be going and marking option "D" and not option "E"
_________________



Math Expert
Joined: 02 Sep 2009
Posts: 58427

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
16 Jul 2012, 05:21
smartmanav wrote: Hi I might be asking a stupid question but then i couldn't stop myself from asking it. Suppose a DS question asks you to find an answer. Lets assume they ask you to find the median of a certain data set with variables in it. based on the two options you have to determine if median >= 5 or not ? If both the option of the question are able to solve it, is it necessary that both questions should get you the same result ? For ex if option A gets the result as median = 5 is it necessary that if option B also is able to get the right answer then it should also get the median value as 5 ?? can there be a possibility that option B gets an answer different than 5 ? Thanks smartmanav Ask a question be a fool for 3 minutes, don't ask n b a fool all your life !!No, scenario you describe is not possible, since on the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other. So, for example in an YES/NO DS question you cannot have a NO answer from the first statement and an YES answer from the second statement or if you are asked to find the value of x, then you cannot get x=5 from the first statement and x=4 from the second statement. Hope it helps.
_________________



Intern
Joined: 10 May 2014
Posts: 1

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
21 Jul 2015, 07:04
Hi,
So in that case, If I arrived at different solutions for the same DS question, Can we say I went wrong somewhere and need to recheck my calculations???
This can actually help in confirming a particular DS question, given that Number proporties (like odd/even) are pretty tricky.
Thanks



Math Expert
Joined: 02 Sep 2009
Posts: 58427

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
21 Jul 2015, 07:17
amritrungta wrote: Hi,
So in that case, If I arrived at different solutions for the same DS question, Can we say I went wrong somewhere and need to recheck my calculations???
This can actually help in confirming a particular DS question, given that Number proporties (like odd/even) are pretty tricky.
Thanks Yes, if you got x = 1 from (1) and x = 2 from (2), then this should be an indication that somewhere you made a mistake.
_________________



CEO
Joined: 20 Mar 2014
Posts: 2595
Concentration: Finance, Strategy
GPA: 3.7
WE: Engineering (Aerospace and Defense)

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
21 Jul 2015, 07:28
Bunuel wrote: smartmanav wrote: Hi I might be asking a stupid question but then i couldn't stop myself from asking it. Suppose a DS question asks you to find an answer. Lets assume they ask you to find the median of a certain data set with variables in it. based on the two options you have to determine if median >= 5 or not ? If both the option of the question are able to solve it, is it necessary that both questions should get you the same result ? For ex if option A gets the result as median = 5 is it necessary that if option B also is able to get the right answer then it should also get the median value as 5 ?? can there be a possibility that option B gets an answer different than 5 ? Thanks smartmanav Ask a question be a fool for 3 minutes, don't ask n b a fool all your life !!No, scenario you describe is not possible, since on the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other. So, for example in an YES/NO DS question you cannot have a NO answer from the first statement and an YES answer from the second statement or if you are asked to find the value of x, then you cannot get x=5 from the first statement and x=4 from the second statement. Hope it helps. Bunuel, this is a very interesting observation you have mentioned. But I have seen in some yes/no DS questions to provide a "no" for 1 statement and "yes" for the other statement and as both statements still give an unambiguous yes or no , the correct answer happens to be D.



Math Expert
Joined: 02 Sep 2009
Posts: 58427

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
21 Jul 2015, 07:52
Engr2012 wrote: Bunuel wrote: smartmanav wrote: Hi I might be asking a stupid question but then i couldn't stop myself from asking it. Suppose a DS question asks you to find an answer. Lets assume they ask you to find the median of a certain data set with variables in it. based on the two options you have to determine if median >= 5 or not ? If both the option of the question are able to solve it, is it necessary that both questions should get you the same result ? For ex if option A gets the result as median = 5 is it necessary that if option B also is able to get the right answer then it should also get the median value as 5 ?? can there be a possibility that option B gets an answer different than 5 ? Thanks smartmanav Ask a question be a fool for 3 minutes, don't ask n b a fool all your life !!No, scenario you describe is not possible, since on the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other. So, for example in an YES/NO DS question you cannot have a NO answer from the first statement and an YES answer from the second statement or if you are asked to find the value of x, then you cannot get x=5 from the first statement and x=4 from the second statement. Hope it helps. Bunuel, this is a very interesting observation you have mentioned. But I have seen in some yes/no DS questions to provide a "no" for 1 statement and "yes" for the other statement and as both statements still give an unambiguous yes or no , the correct answer happens to be D. Such kind of DS questions would be considered flawed as per GMAT standards.
_________________



Director
Affiliations: GMATQuantum
Joined: 19 Apr 2009
Posts: 598

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
22 Jul 2015, 20:35
amritrungta Here are some tacit rules that are followed by GMAT test writers when it comes to Data Sufficiency: 1) The two statements in data sufficiency will never contradict each other. 2) If each statement alone is sufficient, then the outcome will be consistent. This means that if it is a Yes/No data sufficiency question, then both statement will answer the question in the main stem as Yes, or both will answer them as No. If it is a value question, then the outcome will be identical in both cases. 3) If you find that your outcome to the question is different for both the statements, while each statement is sufficient, then you can be guaranteed that either you made some computational error in a value question or you are misinterpreting the statements. This is a valuable tool and I use it to gain further confidence that I did indeed get the data sufficiency question right. Cheers, Dabral



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 15309
Location: United States (CA)

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
22 Jul 2015, 20:36
Hi All, Some of the 'language' in this discussion might be misinterpreted, so I'm going to add some clarification to the discussion. In DS questions, the two Facts CANNOT BOTH be Sufficient with different answers. If you come across this type of situation in a DS question, then the likely reason for it is that your work is INCOMPLETE (so you didn't do enough to prove that one of the Facts was actually Insufficient). Here's a simple example: X is an integer. Is X greater than 0? 1) 3 < X < 0 In this Fact, there are a couple of possible values for X.... IF.... X = 1, then the answer to the question is NO X = 2, then the answer to the question is NO The answer is ALWAYS NO, so.... Fact 1 is SUFFICIENT 2) X^2 = 4 In this Fact, there are a coupe of possible values for X.... IF.... X = 2, then the answer to the question is YES X = 2, then the answer to the question is NO Fact 2 is INSUFFICIENT In this situation, if your work was 'incomplete' in Fact 2 (and you thought that X = 2 was the only solution), then you might think that it's SUFFICIENT (but it's actually NOT  there's another possible value for X that leads to a different answer to the question). Hi Engr2012, If you can 'dig up' any DS questions that match what you describe, then you should post them here. It's possible that the question wasn't properly 'designed' or it's possible that you might have missed something when you attempted to solve it. GMAT assassins aren't born, they're made, Rich
_________________
Contact Rich at: Rich.C@empowergmat.comThe Course Used By GMAT Club Moderators To Earn 750+ souvik101990 Score: 760 Q50 V42 ★★★★★ ENGRTOMBA2018 Score: 750 Q49 V44 ★★★★★



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9701
Location: Pune, India

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
29 Jul 2015, 22:11
amritrungta wrote: Hi,
So in that case, If I arrived at different solutions for the same DS question, Can we say I went wrong somewhere and need to recheck my calculations???
This can actually help in confirming a particular DS question, given that Number proporties (like odd/even) are pretty tricky.
Thanks Absolutely! The two statements will not contradict so if you get different answers, you must recheck your logic/calculations. In fact, I have discussed an advanced DS strategy based on this property of GMAT DS questions here: http://www.veritasprep.com/blog/2014/07 ... tpartii/
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >



Intern
Joined: 03 Nov 2015
Posts: 7

Answer D if both are sufficient
[#permalink]
Show Tags
03 Nov 2015, 14:42
I just read for 'calculate value questions' like 1/(x + 4)? that you should not overthink and just check if statement 1 and 2 are sufficient to calculate x and I agree. However, I was wondering if both statements alone are sufficient, if it is always D, or can the answers be dissimilar (so you have to calculate exactly)?
Post scriptum: Apologies if this is frequently asked



Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4472

Re: Answer D if both are sufficient
[#permalink]
Show Tags
03 Nov 2015, 14:59
neenpaques wrote: I just read for 'calculate value questions' like 1/(x + 4)? that you should not overthink and just check if statement 1 and 2 are sufficient to calculate x and I agree. However, I was wondering if both statements alone are sufficient, if it is always D, or can the answers be dissimilar (so you have to calculate exactly)?
Post scriptum: Apologies if this is frequently asked Dear neenpaques, I'm happy to respond. Here's a blog article with some DS tips. http://magoosh.com/gmat/2013/gmatdata ... encytips/If the DS question is a "find the value of the expression" question, and if you have enough information to calculate the solution from each statement, then the answer always will be (D). In a real GMAT DS or in a high quality practice question, the two statements always will lead to the same value for the expression in the prompt. If you stumble upon a DS practice question in which the two statements lead to different values of the prompt, then that's something that should make you question the validity of that particular source of questions. As I am sure you are aware, not every car company that says, " We sell the best car on the road!" is actually selling the best car on the road. Much in the same way, not every GMAT prep company that says " We have high quality questions that are GMATlike" actually has high quality, GMATlike practice questions. Be a thoughtful and discerning consumer of GMAT practice questions. Does all this make sense? Mike
_________________
Mike McGarry Magoosh Test PrepEducation is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)



CEO
Joined: 20 Mar 2014
Posts: 2595
Concentration: Finance, Strategy
GPA: 3.7
WE: Engineering (Aerospace and Defense)

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
03 Nov 2015, 15:01
neenpaques wrote: I just read for 'calculate value questions' like 1/(x + 4)? that you should not overthink and just check if statement 1 and 2 are sufficient to calculate x and I agree. However, I was wondering if both statements alone are sufficient, if it is always D, or can the answers be dissimilar (so you have to calculate exactly)?
Post scriptum: Apologies if this is frequently asked That is a very good question and a question that has been answered by experts above. As for your question, for official GMAT questions, if both statements are sufficient individually, then you must get the same unique value. This is actually a fun way of checking when you do end up with D for a question asking you a particular value of 'x'. So if you see that you are getting 2 different values of x individually, then recheck your solution. Hope this helps.



SVP
Joined: 06 Nov 2014
Posts: 1873

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
03 Nov 2015, 20:20
neenpaques wrote: I just read for 'calculate value questions' like 1/(x + 4)? that you should not overthink and just check if statement 1 and 2 are sufficient to calculate x and I agree. However, I was wondering if both statements alone are sufficient, if it is always D, or can the answers be dissimilar (so you have to calculate exactly)?
Post scriptum: Apologies if this is frequently asked Hi neenpaques, This is a question that has troubled many test takers. But the bottom line is  If you encounter an official question or a question that has high standards as those of the official questions, then you will always find the values to be same from both the statements. The answer will be D always.



Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 9701
Location: Pune, India

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
03 Nov 2015, 21:20
neenpaques wrote: I just read for 'calculate value questions' like 1/(x + 4)? that you should not overthink and just check if statement 1 and 2 are sufficient to calculate x and I agree. However, I was wondering if both statements alone are sufficient, if it is always D, or can the answers be dissimilar (so you have to calculate exactly)?
Post scriptum: Apologies if this is frequently asked I like to explain this concept in this way: A DS question is a puzzle. For example: Given that x > 0, what is the value of x? Now, from the question stem alone, you will not be able to get a unique value of x. So you cannot answer the puzzle. x could be 1 or 5 or 1000 or 674828.45 etc. So, to help you get to the answer, you have two hint statements given to you. Statement 1: x^2 + x  2 = 0 On solving, this statement tells you that x is either 2 or 1. Now can you answer the puzzle? Yes. We are given that x is positive and this statement tells us that x is either 2 or 1 so x must be 1. That is the only possible value. In this case, we say that statement 1 alone is sufficient to answer the question and hence answer would be either (A) or (D). Now, think about it: can statement 2 tell you that x is either 4 or 5? No! Both statements are hints which may/may not help you find the answer to the SAME puzzle. x has one value and that is what you need to find. So statement 2 can tell you that x is 1 or 2. It can tell you that x is 1. It can tell you that x is 1, 5 or 7 etc. But is it possible that it does not include that value 1 for x? No! The actual value of x is 1 (which we found from statement 1). Since statement 2 is a hint to the same puzzle, it must include that value 1. Otherwise, it would be an incorrect hint and hence, an incorrect DS question. Hope it helps.
_________________
Karishma Veritas Prep GMAT Instructor
Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >



Director
Status: Professional GMAT Tutor
Affiliations: AB, cum laude, Harvard University (Class of '02)
Joined: 10 Jul 2015
Posts: 707
Location: United States (CA)
Age: 39
GMAT 1: 770 Q47 V48 GMAT 2: 730 Q44 V47 GMAT 3: 750 Q50 V42
WE: Education (Education)

Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
05 May 2016, 20:54
This is how I remember it, a la Johnny Cochran: "If the answer is D, then the numbers must agree." If you're getting D, but with two different answers, then you did something wrong on either condition #1 or condition #2.
_________________
Harvard grad and 99% GMAT scorer, offering expert, private GMAT tutoring and coaching worldwide since 2002. One of the only known humans to have taken the GMAT 5 times and scored in the 700s every time (700, 710, 730, 750, 770), including verified section scores of Q50 / V47, as well as personal bests of 8/8 IR (2 times), 6/6 AWA (4 times), 50/51Q and 48/51V. You can download my official testtaker score report (all scores within the last 5 years) directly from the Pearson Vue website: https://tinyurl.com/y7knw7bt Date of Birth: 09 December 1979. GMAT Action Plan and Free EBook  McElroy TutoringContact: mcelroy@post.harvard.edu (I do not respond to PMs on GMAT Club) or find me on reddit: http://www.reddit.com/r/GMATpreparation



GMAT Tutor
Joined: 24 Jun 2008
Posts: 1803

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
26 Jul 2017, 12:29
I don't have too much to add to the good posts above, but I did want to point out why the two statements must be consistent (in other words, it always needs to be possible that both statements are true at the same time). The question always needs to make logical sense if you use both statements, even when one statement is sufficient alone, because some test takers will combine the statements, because some test takers won't notice that one statement is sufficient. And when you use both statements, and they contradict each other, there is no logically correct answer to a DS question. For example, if you had this DS question: What is the value of x? 1. Either x=2 or x=4 2. Either x=1 or x=3 Note that this is a terrible quality question. Clearly neither statement is sufficient alone, but when you combine them, no value of x is even possible. In that case, most mathematicians would probably say the information is sufficient  you know that no value for x exists. But it's also perfectly logical to say this is insufficient, because you can't find x using the two statements. So there's no good answer to a question like this  you can justify C, and you can justify E. That's why the real GMAT can never include questions where the two statements are contradictory. That said, I've seen dozens of prep company questions which do not observe this design principle. If you ever come across questions like that, you're not studying from realistic material, so find better resources to work with. And Karishma, in the blog post she linked to above, described how you can sometimes take advantage of the consistency of the two statements when solving DS questions. I wanted to offer another example. Say you had this DS question: What is the value of the positive integer k? 1. 110 < k^2 < 135 2. 1202 < k^3 < 1402 If k is a positive integer, Statement 1 is sufficient  11^2 = 121 is the only perfect square in that range, so k = 11. Now, when we look at Statement 2, we know the two statements are consistent. If the only possible value for k, using Statement 1, is 11, then it absolutely must be true that k = 11 is one solution for Statement 2. So even if you don't know what 11^3 is, there's no need to calculate it when you look at Statement 2. You can be completely sure 11^3 is somewhere between 1202 and 1402. Since 10^3 clearly is not in that range (10^3 = 1000), the only question we need to answer is whether k could be 12. It's easy to see that k cannot be 12 just by estimation (12*12*10 = 1440 is already larger than 1402, and 12*12*12 is bigger than 12*12*10), so 11 is the only solution to Statement 2 as well, and the answer is D. And as mentioned above, you can use statement consistency to check your work  if you get contradictory solutions when analyzing each statement separately, you've done something wrong, or you're studying from low quality material.
_________________
GMAT Tutor in Toronto
If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com



NonHuman User
Joined: 09 Sep 2013
Posts: 13412

Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
Show Tags
28 Jan 2019, 06:58
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________




Re: Do both sufficient statements provide the same answer in a DS question
[#permalink]
28 Jan 2019, 06:58






