Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

I'm not sure why you're saying "Why can't statement 2 be a fraction?" when the question stem says "integer Z".

if \frac{Z}{3} is odd, then this means the result is an integer because decimials are neither even nor odd. If we take values for Z that when divided by 3 give us integers, we can use (3, 6, 9, 12, 15, 18, 21...}

The resulting value when each is divided by 3 is {1, 2, 3, 4, 5, 6, 7...}. Lets look at which values for Z give us the odd value...that would be 3, 9, 15, 21..etc. These are also odd. So Z is odd from statement 1.

With statement 2, we have to remember number properties. Odd * Odd = Odd [always!]. So if 3*Z is odd, Z must be odd. Just as simple as that.

vishy007 wrote:

Is integer Z odd?

1. \frac{Z}{3} is odd 2. 3Z is odd

Here OA is D with explanation S2 also implies that Z is odd.

Why can't S2 be a fraction? For example 5/3.

I think answer to this question needs to be changed.

_________________

------------------------------------ J Allen Morris **I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.

The email that comes as GMAT question of the day, says -- 2. 49 is odd. This seemed odd, but looking at the actuals question on this webpage makes it clear about answer being D.

Went for A when I received it as question of the day since 2. 49 is odd seemed quite irrelevant to solve the question. But when I saw the actual question I knew it had to be D

Here we go: z/3 is odd, hence z is odd, it could be 3 or any odd number multiplied by 3. - keep A 3*z - is odd, it could be look above, hence the answer is (D) each answer choices is sufficient. Did not delve deep since it is data sufficiency quesiton Correct me, if I went awry.

Here are a few equations that one needs to absolutely remember. One would be surprised at the number of questions in which these concepts can be applied.

[*]ODD x ODD = ODD The only way to get an odd integer as a result when 2 integers are multiplied is when BOTH the integers are ODD.

As a consequence of the above rule, the division rule also applies [*]ODD/ODD = ODD

ODD x EVEN = EVEN ODD + ODD = EVEN ODD - ODD = EVEN ODD + EVEN = ODD ODD - EVEN = ODD

_________________

----------------------------------------------------------------------------------------------------- IT TAKES QUITE A BIT OF TIME AND TO POST DETAILED RESPONSES. YOUR KUDOS IS VERY MUCH APPRECIATED -----------------------------------------------------------------------------------------------------

Z cannot be a fraction. when GMAT question says 3Z is odd. It is a true statement. For 3Z (or Z/3) to be odd, 3Z (or Z/3) should be an integer. For 3Z (or Z/3) to be an integer, Z should be an integer. From my point of view answer to this question is B. For Z/3 to be odd Z should be a multiple of 3 (like 3,6, 9, 12....) if Z is 3,9,15... result will be odd. otherwise, it is even. So, this statement is not sufficient to answer if Z is odd or not. Correct me if I am wrong.

Z cannot be a fraction. when GMAT question says 3Z is odd. It is a true statement. For 3Z (or Z/3) to be odd, 3Z (or Z/3) should be an integer. For 3Z (or Z/3) to be an integer, Z should be an integer. From my point of view answer to this question is B. For Z/3 to be odd Z should be a multiple of 3 (like 3,6, 9, 12....) if Z is 3,9,15... result will be odd. otherwise, it is even. So, this statement is not sufficient to answer if Z is odd or not. Correct me if I am wrong.

z cannot be a fraction because the stem says that z IS an integer: "is integer z odd?".

Next, if we were not told that z is an integer, then the answer would be A:

(1) \frac{z}{3} is odd --> \frac{z}{3}=odd --> z=3*odd=odd. Sufficient.

(2) 3z is odd --> 3z=odd. Now, if z IS an integer, then it must be odd but if z is say 1/3 (in this case 3z=3*1/3=1=odd), then z is not an odd integer. Not sufficient.

Z cannot be a fraction. when GMAT question says 3Z is odd. It is a true statement. For 3Z (or Z/3) to be odd, 3Z (or Z/3) should be an integer. For 3Z (or Z/3) to be an integer, Z should be an integer. From my point of view answer to this question is B. For Z/3 to be odd Z should be a multiple of 3 (like 3,6, 9, 12....) if Z is 3,9,15... result will be odd. otherwise, it is even. So, this statement is not sufficient to answer if Z is odd or not. Correct me if I am wrong.

z cannot be an integer because the stem says that z IS an integer: "is integer z odd?".

Next, if we were not told that z is an integer, then the answer would be B:

(1) \frac{z}{3} is odd --> \frac{z}{3}=odd --> z=3*odd=odd. Sufficient.

(2) 3z is odd --> 3z=odd. Now, if z IS an integer, then it must be odd but if z is say 1/3 (in this case 3z=3*1/3=1=odd), then z is not an odd integer. Not sufficient.

Hope it's clear.

"Is integer Z odd?" means Z is integer (means not a fraction). Even/Odd applies to only integers. What was is thinking about Z/3. When Z/3 is odd Z should be odd multiple of 3. So, Z is Odd. Sorry for that. Answer is D. Both (I) & (II) alone are sufficient