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Is Integer r even? [#permalink]
06 Jul 2011, 06:51

1

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Difficulty:

5% (low)

Question Stats:

70% (01:48) correct
30% (00:54) wrong based on 10 sessions

If |r| is not equal to 1, is integer r even?

1. r is not positive 2. 2r>-5

This is my approach:

Considering statement 1

r is a negative integer and is not equal to 1. But it can be any other integer. Therefore insufficient.

Considering statement 2

2r>-5

For this to happen r has to be -2, -1, 0,1,2,...n. Therefore r can be either ODD or EVEN. Insufficient.

Combining the two:Yes. How? from Statement 1-> r is negative and not equal to 1 and from statement 2 we can tell r can only be -2 and therefore negative.

The question is again the same - is my approach correct?

Guys - My sincere apologies to everyone on this forum by asking about the approach. As I said before, GMAT did bite me 3 times previously and this time I am not taking any chances as most of you guys said its always best to work on basics first. Therefore, I want to be sure that my concepts are getting better.

Re: Is Integer r even? [#permalink]
06 Jul 2011, 07:05

enigma123 wrote:

If |r| is not equal to 1, is integer r even?

1. r is not positive 2. 2r>-5

This is my approach:

Considering statement 1

r is a negative integer and is not equal to 1. But it can be any other integer. Therefore insufficient.

Considering statement 2

2r>-5

For this to happen r has to be -2, -1, 0,1,2,...n. Therefore r can be either ODD or EVEN. Insufficient.

Combining the two:Yes. How? from Statement 1-> r is negative and not equal to 1 and from statement 2 we can tell r can only be -2 and therefore negative.

The question is again the same - is my approach correct?

Guys - My sincere apologies to everyone on this forum by asking about the approach. As I said before, GMAT did bite me 3 times previously and this time I am not taking any chances as most of you guys said its always best to work on basics first. Therefore, I want to be sure that my concepts are getting better.

Re: Is Integer r even? [#permalink]
03 Aug 2011, 20:26

enigma123,

Your approach to solve this problem is correct. The only correction needed is that when you combine both statements, you take the possible value of r to be only -2, but the value of r can also be 0 (as zero is a non-negative integer. As an aside, it is also non-positive).

Some points to remember: (1) Negative integers too can be even (2) 0 is the only integer that is both non-negative as well as non-positive. If ever you come across a question that asks you to work with non-negative integers, don't just take positive integers as the valid set. Remember to include the zero. Similarly, non-positive integers also include zero _________________