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06 Nov 2014, 09:05
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
85%
(hard)
Question Stats:
43% (01:53) correct
57%
(02:06)
wrong
based on 257
sessions
History
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Not Attempted Yet
Tough and Tricky questions: Algebra.
If a, b, x and y are positive integers, what is the value of a - b?
(1) x^a = x^b + x^b + x^b
(2) y^a = y^b + y^b + y^b + y^b
Kudos for a correct solution.
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
06 Nov 2014, 20:18
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Statement 1:
x^a = x^b + x^b + x^b
x^a=3*x^b
Since all are integer we can say x = 3, 3^a=3^b+1
and therefore a= b+1, a-b=1
Sufficient
Statement 2:
y^a = y^b + y^b + y^b + y^b
y^a = 4^1* y^b
or, y^a = 2^2* y^b
If y=4, a=b+1
If y=2, a =b+2
Hence insufficient
Therefore answer is A
x^a = x^b + x^b + x^b
x^a=3*x^b
Since all are integer we can say x = 3, 3^a=3^b+1
and therefore a= b+1, a-b=1
Sufficient
Statement 2:
y^a = y^b + y^b + y^b + y^b
y^a = 4^1* y^b
or, y^a = 2^2* y^b
If y=4, a=b+1
If y=2, a =b+2
Hence insufficient
Therefore answer is A
06 Nov 2014, 23:49
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Bunuel
Stmn1)
x^a = 3x^b
x^a-b = 3
x=3 , a-b=1
as all are positive integers ,we cant consider x=9 and a-b=1/2
Suff
Stmn2)
y^a = 4y^b
y^a-b= 4
y=4 a-b=1
y=2 a-b=2
Insuff
IMO A
