|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 03 Sep 2012
Posts: 245
Location: United States
Concentration: Healthcare, Strategy
GMAT Date: 02-20-2013
GPA: 3.65
WE: Medicine and Health (Health Care)
Followers: 8
Kudos [?]:
18
[1] , given: 16
|
What is the Units digit of Y [#permalink]
 11 Nov 2012, 01:42
1
This post received
KUDOS
Question Stats:
84% (01:20) correct
15% (00:30) wrong based on 2 sessions
What is the Units digit of Y? (1) The units digit of y^2 = 1 (2) The units digit of y does not equal 1. Source: MGMAT Advanced Quant.
_________________
"When you want to succeed as bad as you want to breathe, then you’ll be successful.” - Eric Thomas
|
|
|
|
|
|
|
|
|
Manager
Joined: 03 Sep 2012
Posts: 245
Location: United States
Concentration: Healthcare, Strategy
GMAT Date: 02-20-2013
GPA: 3.65
WE: Medicine and Health (Health Care)
Followers: 8
Kudos [?]:
18
[0], given: 16
|
Re: What is the Units digit of Y [#permalink]
11 Nov 2012, 01:47
Having a bit of an issue with this DS problem. The question stem DOES NOT tell us that Y is either a Single Digit No. or a two digit number.. (1) The unit digit of y^2 = 1 ... Y therefore could be any one of the following numbers: 1, 9, 11 (11 x 11 = 121 , unit digit of 121 is one), 19, 21, 29.... So statement One is not suff. (2) The units digit of Y does not equal 1. Not suff. Taking 1 and 2 together we can remove the following numbers from the list : 1,11,21,31 etc .. This still leaves, 9 , 19, 29, 39..The squares of all result in a NUMBER whose UNIT digit is 1 .. Why is the official answer ASSUMING that Y has only one digit when it is not mentioned?
_________________
"When you want to succeed as bad as you want to breathe, then you’ll be successful.” - Eric Thomas
|
|
|
|
|
|
Manager
Joined: 02 Nov 2012
Posts: 95
Location: India
Concentration: Entrepreneurship, Strategy
WE: Other (Computer Software)
Followers: 0
Kudos [?]:
26
[1] , given: 35
|
Re: What is the Units digit of Y [#permalink]
11 Nov 2012, 03:07
1
This post received
KUDOS
vomhorizon wrote: Having a bit of an issue with this DS problem.
The question stem DOES NOT tell us that Y is either a Single Digit No. or a two digit number..
(1) The unit digit of y^2 = 1 ... Y therefore could be any one of the following numbers:
1, 9, 11 (11 x 11 = 121 , unit digit of 121 is one), 19, 21, 29....
So statement One is not suff.
(2) The units digit of Y does not equal 1.
Not suff.
Taking 1 and 2 together we can remove the following numbers from the list :
1,11,21,31 etc ..
This still leaves, 9 , 19, 29, 39..The squares of all result in a NUMBER whose UNIT digit is 1 ..
Why is the official answer ASSUMING that Y has only one digit when it is not mentioned? Read the question carefully. They are asking the units digit of Y. Not the number Y itself. 9, 19, 29, 39,..... are all values of Y; agreed. But the units digit will always remain 9. Thus, answer is C.
_________________
TH
Give me +1 Kudos if my post helped!
"Follow your passion. Change the world."
|
|
|
|
|
|
Intern
Joined: 11 Nov 2012
Posts: 7
Followers: 0
Kudos [?]:
1
[1] , given: 12
|
Re: What is the Units digit of Y [#permalink]
11 Nov 2012, 03:24
1
This post received
KUDOS
Agree with TH03 response, we need to concentrate on the unit digit as the questions ask for its value in the question. (1) The unit digit of y^2 = 1 . This comes down to either to 1 or 9 as unit digit (the number could be 1,11,21 or 9,19,29 etc) Not sufficient (2) The units digit of Y does not equal 1. This could be anything from 0, 9 except 1 Not suff. Combining both of them we reach the answer is (C) as 9 is the last digit. 
|
|
|
|
|
|
Manager
Joined: 02 Nov 2012
Posts: 95
Location: India
Concentration: Entrepreneurship, Strategy
WE: Other (Computer Software)
Followers: 0
Kudos [?]:
26
[1] , given: 35
|
Re: What is the Units digit of Y [#permalink]
11 Nov 2012, 03:27
1
This post received
KUDOS
avi2crackgmat wrote: Agree with TH03 response, we need to concentrate on the unit digit as the questions ask for its value in the question. Thanks! I would love kudos too! 
_________________
TH
Give me +1 Kudos if my post helped!
"Follow your passion. Change the world."
|
|
|
|
|
|
Manager
Joined: 03 Sep 2012
Posts: 245
Location: United States
Concentration: Healthcare, Strategy
GMAT Date: 02-20-2013
GPA: 3.65
WE: Medicine and Health (Health Care)
Followers: 8
Kudos [?]:
18
[0], given: 16
|
Re: What is the Units digit of Y [#permalink]
11 Nov 2012, 04:06
Thx for the reply..I;ma go smack my head against a wall now ...
_________________
"When you want to succeed as bad as you want to breathe, then you’ll be successful.” - Eric Thomas
|
|
|
|
|
|
Manager
Joined: 12 Oct 2011
Posts: 136
GMAT 1: 700 Q48 V37
GMAT 2: 720 Q48 V40
Followers: 2
Kudos [?]:
37
[0], given: 23
|
Re: What is the Units digit of Y [#permalink]
27 Nov 2012, 07:52
But the question doesn't specify that y has to be an integer. For example y could be 21^1/2, in which case it's unit digit would be 4, or y could be 9, so I think E should be correct.
|
|
|
|
|
|
|
Re: What is the Units digit of Y
[#permalink]
27 Nov 2012, 07:52
|
|
|
|
|
|
|
|
|
|
|
close
