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M11-02

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M11-02  [#permalink]

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New post 15 Sep 2014, 23:43
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A
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C
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Question Stats:

69% (01:00) correct 31% (00:54) wrong based on 143 sessions

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If \(X\) is a three-digit positive integer, what is the value of its tens digit?



(1) The tens digit of \((X + 8)\) is 5.

(2) The units digit of \((X + 9)\) is 7.

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Re M11-02  [#permalink]

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New post 15 Sep 2014, 23:43
Official Solution:


Statement (1) by itself is insufficient. Consider 149 and 150.

Statement (2) by itself is insufficient. We only know that the units digit of \(X\) is 8.

Statements (1) and (2) combined are sufficient. The fact that the units digit of \(X\) is 8 means that the tens digit of \(X + 8\) is 1 greater than the tens digit of \(X\). Thus, the tens digit of \(X\) is 4.


Answer: C
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Re: M11-02  [#permalink]

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New post 25 Oct 2014, 19:20
Hi Bunuel,

This question says 3 digit integer but does not say it is positive or negative.

If it was a negative number then we can have numbers such as -166 it satisfies both stmt 1&2 and if its positive your solution is correct.


I believe the answer to this question should be "E".

Please advice.

Regards,
Arun


Bunuel wrote:
Official Solution:


Statement (1) by itself is insufficient. Consider 149 and 150.

Statement (2) by itself is insufficient. We only know that the units digit of \(X\) is 8.

Statements (1) and (2) combined are sufficient. The fact that the units digit of \(X\) is 8 means that the tens digit of \(X + 8\) is 1 greater than the tens digit of \(X\). Thus, the tens digit of \(X\) is 4.


Answer: C
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Re: M11-02  [#permalink]

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New post 12 Mar 2015, 14:28
Can you explain how tens digit of X + 8 = 5, gives us two options 4 and 5. I would think it should be 6 and 7
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Re: M11-02  [#permalink]

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New post 13 Mar 2015, 05:50
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waqasbinjamal wrote:
Can you explain how tens digit of X + 8 = 5, gives us two options 4 and 5. I would think it should be 6 and 7


If x = 149, then x + 8 = 149 + 8 = 157 --> the tens digit is 5.
If x = 150, then x + 8 = 150 + 8 = 158 --> the tens digit is 5.

Hope it's clear.
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Re: M11-02  [#permalink]

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New post 18 Jun 2015, 08:59
Bunuel wrote:
waqasbinjamal wrote:
Can you explain how tens digit of X + 8 = 5, gives us two options 4 and 5. I would think it should be 6 and 7


If x = 149, then x + 8 = 149 + 8 = 157 --> the tens digit is 5.
If x = 150, then x + 8 = 150 + 8 = 158 --> the tens digit is 5.

Hope it's clear.


Hi Bunuel,

The way the question is written, one may understand that "the whole X" + 8 gives you a tens digit of 5, though one may also understand that X´s tens digit + 8 = 5.
I think that´s what "waqasbinjamal" meant.
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Re: M11-02  [#permalink]

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New post 01 Jul 2015, 06:11
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Hi,

Very interesting... Means that If I know the restriction statement (No what matter it is, for instance: if it is (1) The tens digit of X+3 is 5 or (2) The units digit of X+9 is 3) for all lower digits than the one asked in the question stem, then always is going to be only an answer and then sufficient...

For instance:

If tens digits is asked in question stem, then I should know the restrictions for the lowers: Units and tens, then always will be sufficient no matter what restriction it is... I am talking about X + 1, X + 2, X +3 kind of restrictions. Same thing would happen for hundreds, If I want to know hundreds then I need to know hundreds, tens and units in restrictions in order to have a definite answer... is it true?

Is it correct?

Thanks a lot.

Luis Navarro
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Re: M11-02  [#permalink]

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New post 01 Jul 2015, 09:38
luisnavarro

I may be wrong, but I personally wouldn´t approach it that way. The reason is that you are trying to memorize a rule for a question that can get very tricky or twisted. I would suggest you to set the restriction on paper and start searching for what values make the statement insufficient. At least that is the approach I´ve learnt with Ron (in his videos).
For other types of questions, knowing the rule will help you (such as knowing that |x| = x^2 for X= -1, 1 or 0 only), but not for this one.

Best!
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Re: M11-02  [#permalink]

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New post 01 Jul 2015, 11:29
michaelyb wrote:
luisnavarro

I may be wrong, but I personally wouldn´t approach it that way. The reason is that you are trying to memorize a rule for a question that can get very tricky or twisted. I would suggest you to set the restriction on paper and start searching for what values make the statement insufficient. At least that is the approach I´ve learnt with Ron (in his videos).
For other types of questions, knowing the rule will help you (such as knowing that |x| = x^2 for X= -1, 1 or 0 only), but not for this one.

Best!


Yes, I agree, It is better to be careful with this kind of problems.

Thanks a lot¡¡¡
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Re: M11-02  [#permalink]

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New post 26 Jan 2016, 02:58
Bunuel wrote:
Official Solution:


Statement (1) by itself is insufficient. Consider 149 and 150.

Statement (2) by itself is insufficient. We only know that the units digit of \(X\) is 8.

Statements (1) and (2) combined are sufficient. The fact that the units digit of \(X\) is 8 means that the tens digit of \(X + 8\) is 1 greater than the tens digit of \(X\). Thus, the tens digit of \(X\) is 4.


Answer: C



This looks to be an interesting Q's

Pls suggest me similar Q's
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Re: M11-02 &nbs [#permalink] 26 Jan 2016, 02:58
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