Data Sufficiency

priyasaibaba wrote:Can anyone pls answer this data sufficiency question?

Is x an odd integer?
(1) x + 3 is an even integer.
(2) x/3 is an odd integer.

My solution:

for stmt 1 to be true, 'x' can take values 1,3,5,7...or negative values like -1,-3,-5 etc. (I'm considering 0 as even here)
so stmt 1 is sufficient

for stmt 2 to be true, 'x' can take values 3,9,15,21..or negative values -3,-9,-15,-21 etc.
so whenever x/3 is odd, x is always odd.
stmt2 is also sufficient

So answers d - Both statements are alone sufficient

This is a question of GMAT set 5. The given answer is C.

Can anyone tell me what mistake I'm doing?

Thanks,
Priya

godspeed wrote:Hi

Have you considered values like 30,36,42 .. for the statement 2 ? When you consider these statement 2 will not be sufficient

fibbonnaci wrote:@gmatmachoman,
as u say in statement 2, we cannot use x= 1 , -1 etc since it does not satisfy the criteria.
But our concern is not what numbers satisfy but to identify if the numbers that satisfy the criteria are odd or not.

According to statement 2: all the numbers that satisfy the criteria are odd because of the simple reason, odd * odd => odd

x = 3* odd, therefore X is odd.
This statement in itself is sufficient. we dont even have to consider zero, coz 0/3 -> 0 (which is even and our statement 2 is different)

and from statement 1:
odd+ odd => even
x+3 -> even
therefore this statement in itself is sufficient.

considering zero, you do not disprove the sufficiency. IMO i would go for D and not C

rockeyb wrote:Is x an odd integer?
(1) x + 3 is an even integer.
(2) x/3 is an odd integer.


Now lets rephrase statement (1)

x + 3 = even .

Now you can get an even number result only in following two cases :

(1) odd + odd = even

(2) even + even = even

Now since 3 here is odd "x" has to be odd .

Sufficient.

Govi's explanation:My Issue : Agreed X has to be ODD. If we take X=1, we get X+3 =4. Now try plugging the value of X=1 in St2.It wont give a Odd integer. So you can't use X={-1,0,1}

I am pretty sure in DS, we are supposed to get same Values if we select Option D.
.

gmatmachoman wrote:Fibo & Rockeyb

to simplify our discussion , I request you to drop down the probable values of X.


Can X = 1 or -1?? , if so plz explain!

gmatmachoman wrote:

rockeyb wrote:Is x an odd integer?
(1) x + 3 is an even integer.
(2) x/3 is an odd integer.


Now lets rephrase statement (1)

x + 3 = even .

Now you can get an even number result only in following two cases :

(1) odd + odd = even

(2) even + even = even

Now since 3 here is odd "x" has to be odd .

Sufficient.

Govi's explanation:My Issue : Agreed X has to be ODD. If we take X=1, we get X+3 =4. Now try plugging the value of X=1 in St2.It wont give a Odd integer. So you can't use X={-1,0,1}

I am pretty sure in DS, we are supposed to get same Values if we select Option D.
.

gmatmachoman wrote:Guys,(@harsha,Fibo,Rockey)

Can u plz tell me for st 1 & st 2 what are the range of values of X??

St 1: {-----------}

St2:{--------}

If u post the values, I think our discussion can come to end..

rockeyb wrote:

gmatmachoman wrote:Guys,(@harsha,Fibo,Rockey)

Can u plz tell me for st 1 & st 2 what are the range of values of X??

St 1: {-----------}

St2:{--------}

If u post the values, I think our discussion can come to end..

Any integer that is a multiple of 3 will be set of values for X that will satisfy statement 1 and 2 .

rockeyb wrote:

gmatmachoman wrote:Guys,(@harsha,Fibo,Rockey)

Can u plz tell me for st 1 & st 2 what are the range of values of X??

St 1: {-----------}

St2:{--------}

If u post the values, I think our discussion can come to end..

Any integer that is a multiple of 3 will be set of values for X that will satisfy statement 1 and 2 .