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If A, B and C are digits between 0 and 9 inclusive, what is
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16 Jan 2012, 14:38
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Kaplan Math Workbook (6th Edition) official answer states: statement 1:that a sum of a twodigit number plus another twodigit number gives a threedigit number. The sum of 2 twodigit numbers must be less that 200, therefore A must be 1. Then it concludes that this statement is true only when b=9 > Sufficient Statement 2 is Insufficient (obviously) and therefore the AC is A. Evaluating the red phrase: it assumes that A and B must be twodigit numbers. Isn't it possible that A=0? Isn't the following addition correct? (B has to equal 0 for it to be correct, but still...) + 0 B + B 0  0 0 B Or because no one writes the 0's therefore it implies that A and B can't equal 0? I would really appreciate any comments.





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Re: Ambiguous Kaplan Gmat Math Workbook Question
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16 Jan 2012, 15:04
SonyGmat wrote: Attachment: Kaplan.png Kaplan Math Workbook (6th Edition) official answer states: statement 1:that a sum of a twodigit number plus another twodigit number gives a threedigit number. The sum of 2 twodigit numbers must be less that 200, therefore A must be 1. Then it concludes that this statement is true only when b=9 > Sufficient Statement 2 is Insufficient (obviously) and therefore the AC is A. Evaluating the red phrase: it assumes that A and B must be twodigit numbers. Isn't it possible that A=0? Isn't the following addition correct? (B has to equal 0 for it to be correct, but still...) + 0 B + B 0  0 0 BOr because no one writes the 0's therefore it implies that A and B can't equal 0? I would really appreciate any comments. I think one thing we can assume safely is that A, B and C are distinct digits. Next, even if we don't assume that A>0 (because of AB and AAC as you mention) then still A can not be zero as 0B+B0=00C doesn't hold true for any values of B and C (single digit number B plus twodigit number B0 can not equal to C, also a single digit number). If A, B and C are digits between 0 and 9 inclusive, what is the value of B?(1) AB + BA = AAC > well from above A=1 (A can not be more than 1, as the sum of 2 twodigit numbers is always less than 200) > 1B+B1=11C > B=9 (B can not be less than 8 as 18+81=99, not a three digit number) > 19+91=110. Sufficient. (2) A = 1. Not sufficient. Answer: A. Hope it helps.
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Re: Ambiguous Kaplan Gmat Math Workbook Question
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16 Jan 2012, 16:50
Bunuel wrote: I think one thing we can assume safely is that A, B and C are distinct digits.
Thanks for your post Bunuel! +1 why should we assume that they are distinct digits? Let me try to illustrate my point with another example: Can the sum of two prime numbers, A and B, be an even number? Of course it can. If a=b=2 then 2+2=4. It doesn't state that x and y are distinct values, therefore to my understanding, I can assume that they could have the same value. Now back to my post: Since the question stem doesn't state that A,B,C are distinct values, why should we assume it? isn't it possible for A=B=C=0?



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Re: Ambiguous Kaplan Gmat Math Workbook Question
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16 Jan 2012, 17:13
SonyGmat wrote: Bunuel wrote: I think one thing we can assume safely is that A, B and C are distinct digits.
Thanks for your post Bunuel! +1 why should we assume that they are distinct digits? Let me try to illustrate my point with another example: Can the sum of two prime numbers, A and B, be an even number? Of course it can. If a=b=2 then 2+2=4. It doesn't state that x and y are distinct values, therefore to my understanding, I can assume that they could have the same value. Now back to my post: Since the question stem doesn't state that A,B,C are distinct values, why should we assume it? isn't it possible for A=B=C=0? I agree that it would have been better if they mentioned "distinct" in the stem (to avoid confusion in some testtakers). Having said that, in order your case to be valid 1. we shouldn't consider digits to be distinct (which was quite obvious at least for me) and 2. consider 00+00=000 as a proper option, which is too "technical" and nonconventional way of writing digit 0. Anyway since you understand what was the intended meaning of the question I wouldn't worry about these technicalities at all. On the GMAT you won't see any ambiguous questions at all.
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Re: Ambiguous Kaplan Gmat Math Workbook Question
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20 Jan 2012, 03:08
I have a question about statement number:2]A=1 If A equals one then B has to be 9 , any other number <9, will not give a carryover figure that is required to get AA or (11) so I think statement:2 should also be sufficient. Am I missing something here?
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Re: Ambiguous Kaplan Gmat Math Workbook Question
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20 Jan 2012, 03:18



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Re: If A, B and C are digits between 0 and 9 inclusive, what is
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20 Jan 2012, 03:21



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Re: If A, B and C are digits between 0 and 9 inclusive, what is
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20 Jan 2012, 04:52
SonyGmat wrote: Attachment: Kaplan.png Kaplan Math Workbook (6th Edition) official answer states: statement 1:that a sum of a twodigit number plus another twodigit number gives a threedigit number. The sum of 2 twodigit numbers must be less that 200, therefore A must be 1. Then it concludes that this statement is true only when b=9 > Sufficient Statement 2 is Insufficient (obviously) and therefore the AC is A. Evaluating the red phrase: it assumes that A and B must be twodigit numbers. Isn't it possible that A=0? Isn't the following addition correct? (B has to equal 0 for it to be correct, but still...) + 0 B + B 0  0 0 B Or because no one writes the 0's therefore it implies that A and B can't equal 0? I would really appreciate any comments. The best way to approach this problem is, 1. A and B are interchanged 2 digit number. 2. Most important is, 2 statements cannot contradict each other. Hence A should be equal to 1( Though it is possible that the equation satisfies 1 and any other number). If you plug the number in original equation A= 1 and B =9. Thus A is sufficient. Also, since A and B are 2 digit number, we can use 10A+10B + 10B + A ===> 11(A+B). Right hand side must be multiple of 11 and 3 digit number.



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