GMAT Data Sufficiency Discussions

MBA GMAT
2243
1. If x and y are positive, is the ratio of x to y greater than 3 ?
(1) x is 2 more than 3 times y.
(2) The ratio of 2x to 3y is greater than 2.





Sol-
x = 3y+2
so we have
x/y = (3y+2)/y
= 3+2/y which is greater den 3
Thus statement 1 is alone sufficient

now
2x/3y>2
2x>6y
x>3y
x/y>3

thus statement 1 and 2 are individually sufficient
2244

HI puys....

a question ..

Q:- Does the integer M have a factor A such that 1


(1) M > 10!
(2) 21!+2

2245

Another shoot!!!!!!!!!!!!!

If X & Y are two integers both greater than 1, is X a multiple of Y?

(1) 10Y^2 - 8Y=X
(2) X^2-X is a multiple of Y




2246
Another shoot!!!!!!!!!!!!!

If X & Y are two integers both greater than 1, is X a multiple of Y?

(1) 10Y^2 - 8Y=X
(2) X^2-X is a multiple of Y



Each statement is individually sufficient
. Yes, X is a multiple of Y
2247
Another shoot!!!!!!!!!!!!!

If X & Y are two integers both greater than 1, is X a multiple of Y?

(1) 10Y^2 - 8Y=X
(2) X^2-X is a multiple of Y







if x is a multiple of y
den x = m*y
1) x = 2y(5y-4)
means x = my

Thus 1st statement is enough

now

2) x2-x is a multiple of y
x2-x = ny
x (x-1) = ny
x=ny(x-1)
thus x = my

So both statements are individually sufficient!
2248
HI puys....

a question ..

Q:- Does the integer M have a factor A such that 1


(1) M > 10!
(2) 21!+2


Each statement is individually sufficient
2249
HI puys....

a question ..

Q:- Does the integer M have a factor A such that 1


(1) M > 10!
(2) 21!+2



em not sure but lemme try !

i feel every integer has has its factor less den itself
lyk take any number
78
it has factors 1 2 3 13 26 39 78
2 3 13 26 39 lie between 1 and 78
except for prime numbers as there 1 and d number itself are the only factors

so if d num is greater den 10! duznt give any idea if it ll b a prime

so i think option 2 is ennough to find d soln as there we will find d num and check whether its prme of not!

editing--
2nd option too doesnt give the exact value of M so i think
Both options arent sufficient to derive the answer
2250
HI puys....

a question ..

Q:- Does the integer M have a factor A such that 1


(1) M > 10!
(2) 21!+2



Answer:-- The question doesn't ask us for the exact value but asks us whether the required factors are available or not.

from (1)
M>10!.. there would occur many prime numbers as also stated by other puys... so we cannot clearly state using just option A.

Using (2)
21! = 1*2*3*4*5*6*7.......*19*20*21

hence 21!+2 = 2*(1*3*4*5...*19*20*21 + 1)
21! + 3 = 3*(1*2*4*5...*19*20*21 + 1)
and same for others too till 21! + 21..

so, for all such values of M, we surely have a factor A that lies between 1 and M.

hence the answer is OPTION B
2251

Is x|(1) x + 1| = 2|x - 1
(2) |x - 3 0

Please post with explanation

2252

Ans: C
Statement1: x + 1 = 2|x - 1
case1: x - 1>0 AND x + 1>0. Combining both we get x>1.
Solving for x: x+1 = 2(x-1) => x=3
case2: x-10. Combining both we get -1Solving for x: x+1 = -2(x-1) =>x=1/3
case3: x-1Solving for x: -(x+1) = -2(x-1) =>x=3. Not possible coz xHence, we get 2 different solutions for x. x=3 and x = 1/3.
Hence Not Sufficient.
Statement2: |x - 3 0
=> x 3. Not Sufficient.
Combining Both Statements:
x=1/3. Sufficient.

Is x|(1) x + 1| = 2|x - 1
(2) |x - 3 0

Please post with explanation

2253
Hey puys!


What is the remainder when X^4 + Y^4 divide by 5
A) X-Y divided by 5 gives remainder 1
B) X+Y divided by 5 gives remainder 2
Sorry! don't know the OA. Could you please explain the approach/steps as well.
2254
Hey puys!


What is the remainder when X^4 + Y^4 divide by 5
A) X-Y divided by 5 gives remainder 1
B) X+Y divided by 5 gives remainder 2
Sorry! don't know the OA. Could you please explain the approach/steps as well.

The answer must be E
If You solve for X & Y from both eq

X-Y=5n+1
X+Y=5n+2

Solving for X and Y you will get Y=1/2 and X=(10n+3)/2 where n is a integer, which is arbitrary value so unique solution is not possible.

Alternative approach.

Its not possible to x^4+y^4 convert in term of (x+y) or (x-y) so cant be solved.
2255

Hey this is a DS problem ...pls help in solving with explanations...thnxxx!!!

For any integers x and y, min9x,y0 and max(x,y) denote the minimum and the maximum of x and y, respectively. For example, min(5,2)=2 and max(5,2)=5 . For the integer w, what is the value of min(10,w) ?
1) w=max(20,z) for some integer z
2) w- max(10,w)

2256

I think you mean to write the second statement as w = max(10,w).
If yes, then the ans is "D".
Statement1 gives w>=20. Therefore, min(10,w)=10. Sufficient.
Statement2 gives w>=10. Therefore, min(10,w)=10. Sufficient.

Hey this is a DS problem ...pls help in solving with explanations...thnxxx!!!

For any integers x and y, min9x,y0 and max(x,y) denote the minimum and the maximum of x and y, respectively. For example, min(5,2)=2 and max(5,2)=5 . For the integer w, what is the value of min(10,w) ?
1) w=max(20,z) for some integer z
2) w- max(10,w)
2257
Hey this is a DS problem ...pls help in solving with explanations...thnxxx!!!

For any integers x and y, min9x,y0 and max(x,y) denote the minimum and the maximum of x and y, respectively. For example, min(5,2)=2 and max(5,2)=5 . For the integer w, what is the value of min(10,w) ?
1) w=max(20,z) for some integer z
2) w- max(10,w)


Ans : "D"
1) w=max(20,z) for some integer z - suficiente..
let Z be greater than 20 then w=max(20,z) => w= 20+ a and min(10,20+a) = 10
let Z be smaller than 20 then w=max(20,z) => w=20 and min(10,20) = 10

2) w= max(10,w) then w is neway greater than 10...
min(10,w) = 10 - suficiente..

I felt W was typed instead of Z, so if that is the case
w= max(10,Z) then
if z > 10 , then w = Z and min(10,w) = 10
if z ??? the function is not defined
if z =10 , then the function is not defined
2258

This is an old question on this thread but the answer to it wasn't clearly mentioned, so thought I'd try asking people here..

If the operation # is one of the four operations +, - , * (multiply) and / (divide), is (6 # 2) # 4 = 6 # (2 # 4)?
(1) 3 # 2 > 3
(2) 3 # 1 = 3

Is the answer D ?
1) results in either sign being + or *. Plugging in either works for main equation.
2) results in sign being either * or /. Again plugging into main equation will work.

The earlier posts said E, which I'm not convinced with.

2259
This is an old question on this thread but the answer to it wasn't clearly mentioned, so thought I'd try asking people here..

If the operation # is one of the four operations +, - , * (multiply) and / (divide), is (6 # 2) # 4 = 6 # (2 # 4)?
(1) 3 # 2 > 3
(2) 3 # 1 = 3

Is the answer D ?
1) results in either sign being + or *. Plugging in either works for main equation.
2) results in sign being either * or /. Again plugging into main equation will work.

The earlier posts said E, which I'm not convinced with.

As per eq.1 # could be + or * as in both cases eq is satisfied.
As per eq. 2 # could be * or /.

So the answer is E
2260
This is an old question on this thread but the answer to it wasn't clearly mentioned, so thought I'd try asking people here..

If the operation # is one of the four operations +, - , * (multiply) and / (divide), is (6 # 2) # 4 = 6 # (2 # 4)?
(1) 3 # 2 > 3
(2) 3 # 1 = 3

Is the answer D ?
1) results in either sign being + or *. Plugging in either works for main equation.
2) results in sign being either * or /. Again plugging into main equation will work.

The earlier posts said E, which I'm not convinced with.


I think the answer is A.
From 1, you can see tht # is '*' or '+'. Both of these will satisfy the equation (6 # 2) # 4 = 6 # (2 # 4)
From 2, # is either '*' or '/'. '*' will satisfy the equation but '/' does not.

Hence A.
2261

hello puys, found this interesting article on some other site about DS... sharing this here.
Can someone please quote a good source for practicing DS questions other than OG, Kaplan and princeton?

Ask any business school student - past, present, or prospective - about Data Sufficiency questions, and you are sure to get an immediate reaction. More often than not that reaction will be negative - "I hate Data Sufficiency!" - and even when it is positive - "those are tough questions, but I figured them out and learned to appreciate them" - the reaction will be one of reluctance for the intricacy of these unique questions. This is with good reason - Data Sufficiency questions tend to carry a significant degree of difficulty on the GMAT (as quant scores have risen, the GMAT has begun to feature more Data Sufficiency questions than its traditional 15 out of 37), and because they require a new thought process for most, they offer a greater study challenge than perhaps any other question type on the GMAT.

All of this is intriguing, however, when you look at the Data Sufficiency format closely, because if you break down the question type, it's remarkably clear-cut and honest: "Do you have enough information to answer the question?". Seems fair enough, right? Obviously, the authors of the GMAT can take this seemingly-simple premise and add difficulty to it, but if you focus only on what the question is asking, the testmakers really only have two ways to trick you:

  1. Get you to think that you have enough information when you really don't
  2. Get you to think that you don't have enough information when you really do
The simplicity of the question type - asking when you have enough information to answer the question - lends itself to these two possibilities for you to answer incorrectly.
With this in mind, you can better think of ways that a question will disguise the sufficiency of the information provided:
You think you have enough information, but you really don't

If you make this mistake, you are likely making assumptions about the question that are telling you things about the data that aren't necessarily true. Are you only thinking in terms of integers, or positive numbers? Have you considered the possibility that 0 is a potential value? Ultimately, to avoid this pitfall, you need to get in the habit of looking for the "catch": "I think this is enough information, but what type of situation would give me a different answer?"
You think you don't have enough information, but you really do

These can be even trickier, as the GMAT provides you with statements that don't quite seem like enough information, but if you work through the statement you will find that it's just enough. When you suspect that this is the case - one major clue is that a particular answer choice seems almost too obvious - work through each statement to glean as much information as you can. Often this comes from taking a statement and manipulating the algebra to rephrase the information in a more useful form. Other times, the GMAT will provide you with a valuable clue in the form of the other statement. Consider the question:
A rental car agency purchases fleet vehicles in two sizes: a full-size car costs $10,000, and a compact costs $9,000. How many compact cars does the agency own?
(1) The agency owns 7 total cars
(2) The agency paid $66,000 for its cars
Here, answer choice C seems to be a fairly easy choice - the first statement tells us that the number of full-size cars plus the number of compacts equals 7 (F + C = 7), and the second tells us that the total value is $66,000, or that 10,000F + 9000C = 66000. Having both equations, we know that, with two equations and two variables, we'll be able to solve for the number of compact cars.
Here, the GMAT is likely trying to get us to think that we have less information than we really do - it's not too likely that they would make choice C as easy to get to as it is. To counteract that, we can ask ourselves whether one of the statements is necessary. Statement 1 tells us that the agency has 7 total cars - is that necessary for us to know, or could we derive that from statement 2?
If we assess the information in statement 2 - that the cars cost $66,000 total - let's see if it is even possible that the agency could have bought anything other than 7 cars. If not, then statement 1 is unnecessary. If we try to purchase 8 cars, it stands to reason that if 8 of the cheapest cars cost more than $66,000, it's not possible to purchase 8. 8 of the cheaper cars would be 8 * 9000, or a total of $72,000. Because 8 of even the cheapest cars - substituting any of the cheaper cars with a more expensive one would only increase the total value above $72,000 - costs too much for us to reach the $66,000 total price paid, then it's not possible to purchase 8 cars (or more).
Similarly, if we test the price of 6 of the full-size cars, we may be able to eliminate that possibility. 6*10000 is $60,000, which is not enough for us to reach the $66,000 total price. If we were to substitute a cheaper car for any of the more expensive cars in our set of 6, it would only decrease that total to below $60,000, so we can prove that the agency cannot purchase 6 cars for $66,000.
Because, based on the information in statement 2, the only number of cars that could be purchased is 7, the information in statement 1 doesn't need to be stated explicitly - we already know that from our interpretation of statement 2. Therefore, the correct answer is B.
More important than this question itself is the takeaway, which is that the GMAT likes to shrewdly hide information from you so that you don't think you have it. One great way to test for that is to take the given information from the other statement and test to see if you really need it. The authors of the test know that we'd all prefer the security of too much information, but will reward us for being able to answer the question with just enough data. If you test the given information to see if you could do without it, you can stay one step ahead of the authors on these tricky questions.
Overall, keep in mind that, as clever as these Data Sufficiency questions can be, the authors have only two ways to get you to make a mistake - they can make you think you have enough information when you don't, or make you think don't you have enough information when you actually do. Sure, there are several smaller devices that they can employ to get you to make these mistakes, but if you keep these major factors in mind as you study and take the exam, you will better be able to anticipate where the trap may lie.

thanks
J
2262

hi,

yes u r right.