BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Set 10 Q13

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 127
Joined: Tue Oct 02, 2007 9:35 am
Thanked: 1 times

Set 10 Q13

by arocks » Sun Oct 07, 2007 4:53 am
If x and y are positive, is 3x > 7y?
(1) x > y + 4
(2) -5x < -14y

I think the answer is B. The OA is D.

Stmt2
-5x<-14y or 5x>14y or 2.5x>7y
So stmt2 is suff.

stmt1 - Not sure how statement1 is useful?
Pls explain. Thanks.
Top
Source: — Data Sufficiency |
Master | Next Rank: 500 Posts
Posts: 460
Joined: Sun Mar 25, 2007 7:42 am
Thanked: 27 times

by samirpandeyit62 » Sun Oct 07, 2007 5:41 am
If x and y are positive, is 3x > 7y?

(1) x > y + 4

here if y =2 then x =6 & 3x>7y

y =3 then x =7 so 3x =7y

but if y is greater than 4 then 3x<4y

Hnece this cannot be sufficeint

2) -5x < -14y

i.e 5x > 14y

so we have 2.5x>7y

so suff

Ans should be B
Regards
Samir
Top
Legendary Member
Posts: 503
Joined: Sun Aug 09, 2009 9:53 pm
Thanked: 31 times
Followed by:2 members

by mmslf75 » Thu Dec 31, 2009 9:27 am
arocks wrote:If x and y are positive, is 3x > 7y?
(1) x > y + 4
(2) -5x < -14y

I think the answer is B. The OA is D.

Stmt2
-5x<-14y or 5x>14y or 2.5x>7y
So stmt2 is suff.

stmt1 - Not sure how statement1 is useful?
Pls explain. Thanks.
x > y + 4
Put Y = 0,1,2...
x>4, x>5 , x>6..so on
Put y=0.5
x>4.5

We need to find out : (y/n)
is 3x > 7y?
x>(7/3)y ---- x>2.3 y

for y=0
x>0,
Stmt 1 says x>4 and querstion : Is x > 0... Ans YES

for y=0.5
x> (23/5)y
x> 4.6 y

Stmt 1 is x>4.5 and Question is X > 4.6 y

Answer NO

Therfore B

is the OA
Top
User avatar
GMAT Instructor
Posts: 3225
Joined: Tue Jan 08, 2008 2:40 pm
Location: Toronto
Thanked: 1710 times
Followed by:614 members
GMAT Score:800

by Stuart@KaplanGMAT » Thu Dec 31, 2009 3:29 pm
mmslf75 wrote:
arocks wrote:If x and y are positive, is 3x > 7y?
(1) x > y + 4
(2) -5x < -14y

I think the answer is B. The OA is D.

Stmt2
-5x<-14y or 5x>14y or 2.5x>7y
So stmt2 is suff.

stmt1 - Not sure how statement1 is useful?
Pls explain. Thanks.
x > y + 4
Put Y = 0,1,2...
x>4, x>5 , x>6..so on
Put y=0.5
x>4.5

We need to find out : (y/n)
is 3x > 7y?
x>(7/3)y ---- x>2.3 y

for y=0
x>0,
Stmt 1 says x>4 and querstion : Is x > 0... Ans YES

for y=0.5
x> (23/5)y
x> 4.6 y

Stmt 1 is x>4.5 and Question is X > 4.6 y

Answer NO

Therfore B

is the OA
Some creative math here!

Everyone is ok with (2), so let's just focus on (1).

We know that x and y are both positive, so we can only select positive values (i.e. not y=0).
We also know that x > y + 4

We want to know whether 3x > 7y.

Let's try a really small y and a really big y and see if it matters.

If y = 1, then x > 5. Let's make x as small as possible, 5.000001.

Is 3(5.0000001) > 7(1)? YES.

If y = 1000, then x > 1004. Let's make x as small as possible, 1004.0000001.

Is 3(1004.000001) > 7(1000)? NO.

Since (1) can produce both a YES and a NO, it's insufficient.
Image

Stuart Kovinsky | Kaplan GMAT Faculty | Toronto

Kaplan Exclusive: The Official Test Day Experience | Ready to Take a Free Practice Test? | Kaplan/Beat the GMAT Member Discount
BTG100 for $100 off a full course
Top
Legendary Member
Posts: 503
Joined: Sun Aug 09, 2009 9:53 pm
Thanked: 31 times
Followed by:2 members

by mmslf75 » Fri Jan 01, 2010 5:34 am
Stuart Kovinsky wrote:
mmslf75 wrote:
arocks wrote:If x and y are positive, is 3x > 7y?
(1) x > y + 4
(2) -5x < -14y

I think the answer is B. The OA is D.

Stmt2
-5x<-14y or 5x>14y or 2.5x>7y
So stmt2 is suff.

stmt1 - Not sure how statement1 is useful?
Pls explain. Thanks.
x > y + 4
Put Y = 0,1,2...
x>4, x>5 , x>6..so on
Put y=0.5
x>4.5

We need to find out : (y/n)
is 3x > 7y?
x>(7/3)y ---- x>2.3 y

for y=0
x>0,
Stmt 1 says x>4 and querstion : Is x > 0... Ans YES

for y=0.5
x> (23/5)y
x> 4.6 y

Stmt 1 is x>4.5 and Question is X > 4.6 y

Answer NO

Therfore B

is the OA
Some creative math here!

Everyone is ok with (2), so let's just focus on (1).

We know that x and y are both positive, so we can only select positive values (i.e. not y=0).
We also know that x > y + 4

We want to know whether 3x > 7y.

Let's try a really small y and a really big y and see if it matters.

If y = 1, then x > 5. Let's make x as small as possible, 5.000001.

Is 3(5.0000001) > 7(1)? YES.

If y = 1000, then x > 1004. Let's make x as small as possible, 1004.0000001.

Is 3(1004.000001) > 7(1000)? NO.

Since (1) can produce both a YES and a NO, it's insufficient.

That was great...!! Thanks stuart..

I like the way u used 5.00000001 and 1004.000001 ..wow !
Top
Master | Next Rank: 500 Posts
Posts: 379
Joined: Wed Jun 03, 2009 3:05 am
Thanked: 19 times
Followed by:1 members
GMAT Score:690

by sreak1089 » Fri Jan 01, 2010 8:50 am
I do it this way:

stmt # 1: x > y + 4
=> x-y > 4

lets take x=9, y=4 3x = 27 < 7y = 28
so, 9-4 > 4

lets take x=9, y=2 3x = 27 > 7y = 14
so, 9-2 > 4

Thus stmt # 1 is INSUFFICIENT. (Q.E.D - Quadrat Errat Demonstrandum :)
Top
Post new topic Post Reply
• Page 1 of 1