Data Sufficiency

Harsha,

Bro, If i say X=1 ,it wont fit for st 2...agreed na?? The number we pick shuld satisfy both the conditions all alone.But here it is NOT.

Plz bro,I am tired of this thread....I am going for C only...

https://en.wikipedia.org/wiki/Evenness_of_zero

Plz go thru the link which states zero is even....

gmatmachoman wrote:Harsha,

Bro, If i say X=1 ,it wont fit for st 2...agreed na?? The number we pick shuld satisfy both the conditions all alone.But here it is NOT.

Plz bro,I am tired of this thread....I am going for C only...

https://en.wikipedia.org/wiki/Evenness_of_zero

Plz go thru the link which states zero is even....

buddy, that's where your starting is inappropriate.

YOU don't have to pick a number.

You are GIVEN a number which satisfies a condition.

It may be st1.

OR

St2.

You just have to tell, based on the condition, whether the number is odd.


Again, you should and MUST not pick number.


don't give up ! you should fight till the point you are satisfied.

OK - everyone needs to calm down!

Let's discuss a few key concepts:

1) 0 is an even "uncharged" (i.e. it's neither positive nor negative) integer.

2) In data sufficiency, the statements never contradict each other. However, they can be complementary, i.e. have some solutions in common and some not in common.

3) In DS, the statements are the law; when you evaluate a statement, you think "given that this statement is true, do I have enough information to answer the question?".

Now, to this specific question:

Is x an odd integer?

(1) x + 3 is an even integer.

(2) x/3 is an odd integer.

Step 1: analyze the question.

We see the word "is", we think "yes/no question: a definite "yes" is sufficient, a definite "no" is sufficient, a "sometimes yes/sometimes no" is insufficient".

We need to determine if x is an odd integer. What do we know about x? Absolutely nothing. Could be even, odd or a non-integer (sign is irrelevant for determining oddness/evenness, so we don't care about -/0/+).

Step 2: evaluate the statements.

1) x + 3 is even.

We can translate this just like any other word problem, treating "is" as our equal sign:

x + 3 = even
x = even - 3

Well, an even minus an odd will always be odd; that's a definite "yes" answer: sufficient.

We could have also plugged in numbers - let our even number be 2 and we get:

x = 2 - 3 = -1

which is odd... sufficient.

(Note: on odd/even questions, once you've tried one even or odd number, there's no need to test similar numbers.)

2) x/3 is odd

Again, let's translate to an equation:

x/3 = odd

x = odd * 3

Well, an odd times an odd is always odd - that's a definite "yes" answer: sufficient.

Each statement is sufficient alone, no need to combine, choose (D).

Now, for those confused about the seeming conflict between the statements, there is none. Conflict only exists when the statements cannot generate a common answer to the question. Here, both statements gave us a "definite yes", so we're fine.

Also, the two statements have at least one numerical solution in common (x=3, for example, satisfies both conditions), so again, no conflict.

Wow!!! Thanks Stuart for clearing the air .

Also, the two statements have at least one numerical solution in common (x=3, for example, satisfies both conditions), so again, no conflict.

It seems I am not the only one talking about 3 and multiples of 3 .

Phew !!!! that settles it .

Thanks a ton Stuart once again.