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yogirb8801
Joined: 28 Aug 2012
Last visit: 28 Apr 2014
Posts: 17
Given Kudos: 6
Location: United States
Concentration: General Management, Leadership
Schools: Thunderbird '16
GPA: 3.37
WE:Information Technology (Consulting)
16 May 2013, 08:19
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C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
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Question Stats:
51% (02:06) correct
49%
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If for integers a, b, c, and d, a + b + c + d = 4, does d = 1?
(1) abc = 1
(2) ad = 1
(1) abc = 1
(2) ad = 1
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
16 May 2013, 08:54
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yogirb8801
Given :- a+b+c+d = 4
asking:- is d = 1??
AD/BCE
statement 1:- abc = 1
Two cases are possible
a=1,b=1,c=1 then d = 1 YES
a=-1,b=-1,c=1 then d= 5 NO
So A alone is not sufficient . AD are ousted.
statement2:- ad = 1
Two cases are possible
a = 1,d = 1 YES
a = -1,d=-1 NO.
so B alone is not sufficient B is ousted
Combine both the statements.
We will get only one case possible which satisfies all the three conditions.
How??
ad = 1 implies two cases a=-1,b=-1 or a=1,b=1
if a=-1 and d = -1 then apply the first condition. then b,c will have -1 and 1 It doesnot satisfy a + b+c+d = 4;
if a=1 and d = 1 then apply second condition then b,c will have 1 ,1 .It satisfies a+b+c+d = 4.So d = 1. YES
SO the answer is C
16 May 2013, 08:55
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If for integers a, b, c, and d, a + b + c + d = 4, does d = 1?
(1) abc = 1. Since each unknown is an integer, then either a=b=c=1 or two of them equal 1 and the third one -1. Now, if a=b=c=1, then d=1 but if a=b=-1 and c=1, then d=5. Not sufficient.
(2) ad = 1 --> a=d=1 or a=d=-1. Not sufficient.
(1)+(2) The common value of d from (1) and (2) is 1. Sufficient.
Answer: C.
Hope it's clear.
(1) abc = 1. Since each unknown is an integer, then either a=b=c=1 or two of them equal 1 and the third one -1. Now, if a=b=c=1, then d=1 but if a=b=-1 and c=1, then d=5. Not sufficient.
(2) ad = 1 --> a=d=1 or a=d=-1. Not sufficient.
(1)+(2) The common value of d from (1) and (2) is 1. Sufficient.
Answer: C.
Hope it's clear.
