GMAT Data Sufficiency Discussions

sdt83 · September 1, 2009, 7:01am

If x not equal to -y, is (x-y)/(x+y)>1 ?

1) x>0
2) y
I feel the answer should be B. When you know Y Any inputs?

Hey.. i've a doubt on d q itself.. Is it x not equal to -y ?? i suppose it sud be x not equal to y..coz if x not equal to -y , dat means x can be equal to y. In dat case q itself will be absurd..0>1!!!

sdt83 · September 1, 2009, 7:17am

neways ... d ans must be E..

stat1. plug some values for x & y.

say x=5 , y=3 then (x-y)/(x+y) x=5, y=-3 then (x-y)/(x+y)>1
so insuff.
stat 2.
x= 3, y= -2 then (x-y)/(x+y)>1
x=-3, y= -2 then(x-y)/(x+y)insuff.

now combine stat1 &sta2; , again insuff.. ( plug x=3 & y=-2 , x=2 & y=-5)

ash16 · September 1, 2009, 7:18am

Stat 1-->Dist. b/w A and B is 25...
this can only be possible if C lies b/w A and B.
so suff...

Stat 2-->B can lie anywhere either b/w A and C or outside..
SO not sufficient

hence IMO (A)

From 1 ) c lies b/w A & B for any permutation.
From 2) c can be either b/w A & B or outside..

So statement 1 itself is sufficient.
Answer is A..

ash16 · September 1, 2009, 7:22am

answer must be option C

For finding the median of set of values, one needs to know the values.. here using option 1 and option 2 we can find out the price of Sue's house.. and once we find that out we can find the median value from the set of 3 values..

lemme know the OA ;)

say three prices are T, J, S
then (T+J+S)/3 = 120
t+J+S = 360
now taking 1), T = 110
S + J = 250,, now S and J can take so many values
e.g. S = 100, J = 150
or S = 50, J = 200
or S = 120, J = 130
so median can vary dependin on these values e.g, fr these three cases ,,
median will be 110, 110, 120 respectively
so cant say
taking 2) J = 120
T+S = 240
now fr T and S, options are
i) T=S = 120,, median = 120
ii) T120,, means J is median and hence median = 120
iii) S120,, means J is median and hence median = 120
so 2) is sufficient

padmalathas · September 1, 2009, 8:43pm

What is the value of (2t+t-x)/(t-x)?
(1) 2t/(t-x) = 3
(2) t x = 5

padmalathas · September 1, 2009, 9:26pm

neways ... d ans must be E..

stat1. plug some values for x & y.

say x=5 , y=3 then (x-y)/(x+y) x=5, y=-3 then (x-y)/(x+y)>1
so insuff.
stat 2.
x= 3, y= -2 then (x-y)/(x+y)>1
x=-3, y= -2 then(x-y)/(x+y)insuff.

now combine stat1 &sta2; , again insuff.. ( plug x=3 & y=-2 , x=2 & y=-5)

Thanks!

I should not have rephrased it like : Is (X - Y) > (X + Y)

nemo1 · September 1, 2009, 9:30pm

What is the value of (2t+t-x)/(t-x)?
(1) 2t/(t-x) = 3
(2) t x = 5

the correct option wud be: (A) as we get a value of 4.the 2nd option is insufficient for arriving at the answer.

deepakraam · September 2, 2009, 4:22am

What is the value of (2t+t-x)/(t-x)?
(1) 2t/(t-x) = 3
(2) t x = 5

we have to find the value of expr (3t-x)/(t-x)

Statement 1:
==========
2t = 3t-3x ====> t = 3x.Substituting the value of t in the above expr we get 4.

so statement 1 is suff

Statement 2:
==========

t-x = 5..Nt suff.

so for the above q I will go with option A

padmalathas · September 2, 2009, 11:53am

If, on a coordinate plane, point A has the coordinates (-3,4), how far is point A from point E?

1) Point E is on the Y axis four units from the origin.
2) If point A were twice as far from point E, it would be the distance from point E as point C is at coordinates (0,-2)

nemo1 · September 2, 2009, 1:17pm

If, on a coordinate plane, point A has the coordinates (-3,4), how far is point A from point E?

1) Point E is on the Y axis four units from the origin.
2) If point A were twice as far from point E, it would be the distance from point E as point C is at coordinates (0,-2)

either statement is sufficient. therefore option: (A)

1) we can get the distance from the first option by directly applying the distance formula. hence, sufficient.

2) from the second option, the distance between point A & E is basically twice the distance between that of E & C. we do not know this as the co-ordinates of E are unknown. hence, insufficient.

pawank_iit · September 2, 2009, 4:35pm

either statement is sufficient. therefore option: (A)

1) we can get the distance from the first option by directly applying the distance formula. hence, sufficient.
Point E can be (0,-4) and (0,4). Hence we can't be sure about the distance between A and E.

2) from the second option, the distance between point A & E is basically twice the distance between that of E & C. we do not know this as the co-ordinates of E are unknown. hence, insufficient.

If we combine 1 and 2 then point E should be (0,4). Hence distance between A and E is 3 and E and C is 6.
Hence we need both the statements.

PS: I am not sure about my understanding of the second point.

pingu · September 2, 2009, 4:51pm

If, on a coordinate plane, point A has the coordinates (-3,4), how far is point A from point E?

1) Point E is on the Y axis four units from the origin.
2) If point A were twice as far from point E, it would be the distance from point E as point C is at coordinates (0,-2)

Good Point Pawank, I missed the pt(0,-4). I would go for option - C. Having said that I think Option 2 is ambiguous. As it seemed to me that AE= twice of (AC or EC), But after solving for(0,4) AE=1/2 of EC .

Padma could you post the explanation?

padmalathas · September 2, 2009, 6:37pm

Good Point Pawank, I missed the pt(0,-4). I would go for option - C. Having said that I think Option 2 is ambiguous. As it seemed to me that AE= twice of (AC or EC), But after solving for(0,4) AE=1/2 of EC .

Padma could you post the explanation?

OA is C indeed!

Actually even I had the similar doubt on statement 2. I thought the same way as Pingu did and marked B. That is why I thought of posting here..

friend9921 · September 3, 2009, 2:55pm

X and Y are both negative integers. Is XY 1. XY = 35
2. X = Y - 2

siddharthaduggirala · September 3, 2009, 3:01pm

X and Y are both negative integers. Is XY 1. XY = 35
2. X = Y - 2

IMO A.

from 1) we have a value that is clearly greater than 1. so suff

From 2) we have x = y-2 and x is -ve so

let x = -1 so y = -3 hence xy> 1
let x = -.1 so y=-2.1 so xy
Hence A.

friend9921 · September 3, 2009, 3:10pm

IMO A.

Hence A.

OA says only statement 2 sufficient.

2. X=Y-2; Y=X+2; Y>X
As both X and Y are negative, we get, YY1 for sure. Thus statement 2 sufficient.

For statement 1, the OA says value of XY cannot be determined:shocked:.

friend9921 · September 3, 2009, 3:12pm

Another two,

Is X greater than Y?
1. 6X=5Y
2. X^2 X - |Y
2. X|>X AND Y=Y

Adding another DS question.

In how many ways can 4 people A, B, C and D be seated such that B and C are always together.
1. A, B, C and D are to be seated in a row.
2. The distance between any person and his neighbour is 5 feet.

siddharthaduggirala · September 3, 2009, 4:07pm

OA says only statement 2 sufficient.

2. X=Y-2; Y=X+2; Y>X
As both X and Y are negative, we get, YY1 for sure. Thus statement 2 sufficient.

For statement 1, the OA says value of XY cannot be determined:shocked:.

:splat::splat::splat::shocked::shocked::shocked:

missed the integer part. I have to kick myself.

siddharthaduggirala · September 3, 2009, 4:25pm

Another two,

Is X greater than Y?
1. 6X=5Y
2. X^2here from 1) we have x =5/6*y

so insuff.because we dont kow whether x, y are + ve or -ve.

from 2 we dont know whether x, y are + ve or -ve.

even combining we dont get a clear answer.

So E.

Is X greater than Y?
1. X - Y > X - |Y
2. X|>X AND Y=Y

1) is clearly insuff.

from 2) we know that x is -ve and y is +ve so suff

hence B

Adding another DS question.

In how many ways can 4 people A, B, C and D be seated such that B and C are always together.
1. A, B, C and D are to be seated in a row.
2. The distance between any person and his neighbour is 5 feet

from 1) we have the number of arrrangements as 3!*2!. so suff

from 2) we dont get any info.

SO A.
.

See my answers in Red.

pawank_iit · September 3, 2009, 4:32pm

Another two,

Is X greater than Y?
1. 6X=5Y
2. X^2

1. x = (5/6) * Y
if y>0 then xy
So 1 is not sufficient.

2. x^2 Here also, if y>0 then xy. Hence 2 is not sufficient.

If we combine 1 and 2 then
(25/36) y ^2 0 or y
Hence there is no solution.