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If a and b are positive integers, is ab an even?
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30 Aug 2016, 20:21
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63% (01:32) correct 37% (01:58) wrong based on 229 sessions
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If a and b are positive integers, is ab an even? 1) (a+1)b=even 2) (a+1)^b=odd *An answer will be posted in 2 days.
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Re: If a and b are positive integers, is ab an even?
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30 Aug 2016, 21:18
MathRevolution wrote: If a and b are positive integers, is ab an even? 1) (a+1)b=even 2) (a+1)^b=odd
*An answer will be posted in 2 days. is \(ab\) an even ? which mean only \(a\) or only \(b\) or both \(a\) and \(b\) are even. 1) \((a+1)b\) = even, which can mean, \(b\) alone is even or \(a\) alone is odd or both \(b\) is even and \(a\) is odd. Not sufficient. Eliminate A and D 2) \((a+1)^b\) = odd, which means no matter what \(b\) is , \(a\) has to be even. Sufficient. Answer is B.



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Re: If a and b are positive integers, is ab an even?
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30 Aug 2016, 22:40
MathRevolution wrote: If a and b are positive integers, is ab an even? 1) (a+1)b=even 2) (a+1)^b=odd
*An answer will be posted in 2 days. st1 : a=1,b=1 NO and a=1,b=2 YES INSUFF st2: a has to be even for statement to be odd SUFF B
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Re: If a and b are positive integers, is ab an even?
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01 Sep 2016, 17:32
Since there are 2 variables in the original condition, the answer is C. However, we have to apply common mistake type 4(A) because it is one of key questions. In case of con 2), from a+1=odd, a=even, the answer is always yes and the condition is sufficient. Hence, the correct answer is B.
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Re: If a and b are positive integers, is ab an even?
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01 Jan 2017, 10:03
Nice Question. Here is my solution to this one >
Given data > A and B are positive integers We need to see if atleast one of them is even or not (so that A*B will be even)
Statement 1> A=odd B=odd NO A=even B=even YES Hence not sufficient
Statement 2=> Positive exponent do not effect the even odd nature of any number Hence A+1 must be odd => A must be even => AB will be even
Hence sufficient
Hence B
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If a and b are positive integers, is ab an even?
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09 Mar 2017, 21:28
 Statement 1 = (a+1)b=even
Lets try a=odd (odd+1)b=even even*b=even b=even/even b=even
Now lets try a=Even (Even+1)b=even odd*b=even b=even/odd b=even
When a=odd, b=even When a=even, b=even
Odd x even = even even x even = even
hence in either case a*b=even  Sufficient to answer
Statement 2 (a+1)^b=odd 
Positive exponent do not effect the even odd nature of any number Hence A+1 must be odd => A must be even => AB will be even
Hence Answer should be D Each alone is sufficient.



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Re: If a and b are positive integers, is ab an even?
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10 Mar 2017, 02:51
St 1: (a+1)b is even that mean either of one is even or both are even. INSUFFICIENT St 2: (a+1)^b is odd. thane means a+1 is odd, hence a is even.therefore ab will be even.ANSWER Option B
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Re: If a and b are positive integers, is ab an even?
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10 Mar 2017, 08:21
I don't agree to reply above that says St 1: (a+1)b is even that mean either of one is even or both are even. INSUFFICIENT
even if either one is even or both are even final question asks is ab even?
If you look at even odd multiplication as below Odd x even = even even x even = even
you're getting answer as even SUFFICIENT



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Re: If a and b are positive integers, is ab an even?
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04 Oct 2018, 08:39
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Re: If a and b are positive integers, is ab an even?
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