GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 19 Dec 2018, 08:49

# TODAY:

MIT Sloan R1 Decisions - Join MIT Chat for Live Updates | Chat with UCLA Anderson Adcom @9am PT | Chat with Yale SOM R1 Admit 10am PT

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

## Events & Promotions

###### Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### Happy Christmas 20% Sale! Math Revolution All-In-One Products!

December 20, 2018

December 20, 2018

10:00 PM PST

11:00 PM PST

This is the most inexpensive and attractive price in the market. Get the course now!
• ### Key Strategies to Master GMAT SC

December 22, 2018

December 22, 2018

07:00 AM PST

09:00 AM PST

Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.

# M11-02

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 51307

### Show Tags

15 Sep 2014, 23:43
00:00

Difficulty:

25% (medium)

Question Stats:

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

### HideShow timer Statistics

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.

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 51307

### Show Tags

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.

_________________
Intern
Joined: 22 Jul 2013
Posts: 19
Location: United States
Concentration: Technology, Entrepreneurship
Schools: IIM A '15
GMAT 1: 650 Q46 V34
GMAT 2: 720 Q49 V38
GPA: 3.67
WE: Engineering (Non-Profit and Government)

### Show Tags

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".

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.

Intern
Joined: 08 Apr 2013
Posts: 2

### Show Tags

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
Math Expert
Joined: 02 Sep 2009
Posts: 51307

### Show Tags

13 Mar 2015, 05:50
1
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.
_________________
Intern
Joined: 11 Nov 2014
Posts: 34
Concentration: Technology, Strategy
GMAT 1: 660 Q48 V31
GMAT 2: 720 Q50 V37
GPA: 3.6
WE: Consulting (Consulting)

### Show Tags

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.
Intern
Joined: 24 Jun 2015
Posts: 46

### Show Tags

01 Jul 2015, 06:11
1
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
Looking for 700
Intern
Joined: 11 Nov 2014
Posts: 34
Concentration: Technology, Strategy
GMAT 1: 660 Q48 V31
GMAT 2: 720 Q50 V37
GPA: 3.6
WE: Consulting (Consulting)

### Show Tags

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!
Intern
Joined: 24 Jun 2015
Posts: 46

### Show Tags

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¡¡¡
Manager
Joined: 03 Aug 2015
Posts: 53
Concentration: Strategy, Technology
Schools: ISB '18, SPJ GMBA '17
GMAT 1: 680 Q48 V35

### Show Tags

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.

This looks to be an interesting Q's

Pls suggest me similar Q's
Re: M11-02 &nbs [#permalink] 26 Jan 2016, 02:58
Display posts from previous: Sort by

# M11-02

Moderators: chetan2u, Bunuel

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.