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GRE Math Challenge #38-consecutive positive integers & a < b
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09 Sep 2014, 01:27
09 Sep 2014, 01:27
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Question Stats:
77% (01:20) correct
22% (01:02) wrong based on 22 sessions
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If a, b & c are consecutive positive integers & a < b < c, which of the
following must be an odd integer?
A. abc
B. a+b+c
C. a+bc
D. a(b+c)
E. (a+b)(b+c)
following must be an odd integer?
A. abc
B. a+b+c
C. a+bc
D. a(b+c)
E. (a+b)(b+c)
Re: GRE Math Challenge #38-consecutive positive integers & a < b
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15 Jan 2018, 02:08
15 Jan 2018, 02:08
i took so long for plugging number into each condition, i'd like to see what other solution you guys have, thank you!
Re: GRE Math Challenge #38-consecutive positive integers & a < b
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15 Jan 2018, 05:01
15 Jan 2018, 05:01
1
the addition or a product of two numbers can result in a odd number in the following 2 circumstances
even+odd= odd
odd+even= odd
odd*odd = odd
consecutive integers are in the format
odd,even,odd
even,odd,even
abc= (a*b)*c = ab must be even hence abc must be even
If a,b,c are in the form odd,even,odd for eg. 1,2,3 then a+b = odd and c will be odd therefore a+b+c will be even
If a,b,c are in the form even,odd,even eg. 2,3,4 then, bc=even and a+bc =even
If If a,b,c are in the form even,odd,even eg.2,3,4 then,a(b+c) = 2(3+4) = 14=even
(a+b)(b+c) follows (odd+even)(even+odd) or (even+odd)(odd+even) in both scenarios the final product will be odd*odd = odd
(E)
even+odd= odd
odd+even= odd
odd*odd = odd
consecutive integers are in the format
odd,even,odd
even,odd,even
abc= (a*b)*c = ab must be even hence abc must be even
If a,b,c are in the form odd,even,odd for eg. 1,2,3 then a+b = odd and c will be odd therefore a+b+c will be even
If a,b,c are in the form even,odd,even eg. 2,3,4 then, bc=even and a+bc =even
If If a,b,c are in the form even,odd,even eg.2,3,4 then,a(b+c) = 2(3+4) = 14=even
(a+b)(b+c) follows (odd+even)(even+odd) or (even+odd)(odd+even) in both scenarios the final product will be odd*odd = odd
(E)
