Last visit was: 21 Jul 2024, 21:33 It is currently 21 Jul 2024, 21:33
Toolkit
GMAT Club Daily Prep
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

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.

# If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4

SORT BY:
Tags:
Show Tags
Hide Tags
Manager
Joined: 27 Dec 2009
Posts: 104
Own Kudos [?]: 830 [24]
Given Kudos: 3
Math Expert
Joined: 02 Sep 2009
Posts: 94441
Own Kudos [?]: 642840 [7]
Given Kudos: 86716
General Discussion
Manager
Joined: 26 Feb 2010
Posts: 54
Own Kudos [?]: 15 [1]
Given Kudos: 1
Location: Argentina
Q47  V28 GMAT 2: 680  Q48  V35
Manager
Joined: 28 Jul 2011
Posts: 128
Own Kudos [?]: 423 [1]
Given Kudos: 16
Re: If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4 [#permalink]
1
Kudos
Vote for E

i did it this way

(A) when Z < 9

if (Z = 8 and t = -1/2)

zt < -3 = true

Z < 4 (NO)

if (Z = 2 and t = -1/2)

zt < -3 = true

Z < 4 (Yes)

Data not sufficient

----------------------------

(B) t < -4

if (Z = 8 and t = -5)

zt < -3 = true

Z < 4 (NO)

if (Z = 2 and t = -5)

zt < -3 = true

Z < 4 (Yes)

Data not sufficient

-----------------------------

(C) combine when Z < 9 and t < -4

if (Z = 8 and t = -5)

zt < -3 = true

Z < 4 (NO)

if (Z = 2 and t = -5)

zt < -3 = true

Z < 4 (Yes)

Data not sufficient

there for E
Retired Moderator
Joined: 29 Oct 2013
Posts: 220
Own Kudos [?]: 2067 [1]
Given Kudos: 204
Concentration: Finance
GPA: 3.7
WE:Corporate Finance (Retail Banking)
If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4 [#permalink]
1
Kudos
Bunuel wrote:
naveenhv wrote:
If zt < -3, is z < 4 ?

(1) z < 9
(2) t < -4

Number picking would probably be the most efficient way to attack this problem. Even when we consider both statements together we can easily find two sets of numbers which give us different answers to the question whether z<4:

If z=5 and t=-5 (zt=-25<-3) the answer is NO;
If z=1 and t=-5 (zt=-5<-3) the answer is YES.

Hi Bunuel and other experts,

When you do this(number picking) it seems so simply! However, number picking is my Achilles' Heel. It is just so frustratingly difficult for me to come up with right numbers.

When I micro-analyze my thinking process while I try to come up with right values to show counter examples this is what I see: I first need to ensure z <9 and then make sure that t < -4 and then ensure that zt< -3 with the aim of getting a NO for z<4. Even though I am using 'then' after every decision, the fact is- to generate right values, you essentially need to make these 4 decisions simultaneously. I simply dont know how I can do this in 20-30 seconds without befuddling my short term memory apparatus. I am saying 20-30 secs as in most of the hard questions you will have to rule out st-A, st-B and A+B. thus you will make 5-6 such decisions for every question.

When I solve such questions I am either totally flustered or take more than 4 mins. Are there efficient ways to do this and which will work for most of the hard problems (inequality, modulus, reciprocal, neg/pos and their combination) etc..in less than 2-3 mins?
Thanks!
Intern
Joined: 25 Oct 2014
Posts: 5
Own Kudos [?]: [0]
Given Kudos: 0
Re: If zt < -3, is z < 4 [#permalink]
ajaym28 wrote:
If zt < -3, is z < 4 ?
(1) z < 9
(2) t < -4

zt < -3 implies either z>0 and t<0 or z<0 and t>0
(1) we ain't told anything abt t... Also, z can be 2 or 4 producing a Y/N cases
(2) at least we know t is <0; but we dont know whether z>4 or <4.

Both alone insufff.

Taken together, tsst: z=2, t=-5 we get zt = -10 (<-3)
Response to stem is Yes, z < 4

Also, take z=4 and t=-5 we get zt = -20 (<-3)
Response is No z is not < 4.

So, E should be OA.
Director
Joined: 29 Jun 2017
Posts: 776
Own Kudos [?]: 401 [0]
Given Kudos: 2198
Re: If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4 [#permalink]
i missed this question.
this test a basic point
t<-4 so we divide both side by t and change the way of equality
zt<-3
z>-3/t=-3/-4=3/4
insufficient.
Manager
Joined: 03 Sep 2018
Posts: 175
Own Kudos [?]: 93 [0]
Given Kudos: 924
Location: Netherlands
GPA: 4
If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4 [#permalink]
$$zt<-3 \ \cap \ z<4$$ $$\implies z(t+1)<1$$

$$Combining \ both \ statements:$$

$$z=8, t=-5 \implies 8(-5)<1 \implies (YES)$$

$$z=-9, t=-5 \implies -8(-5)<1 \implies (NO)$$
Senior Manager
Joined: 16 Nov 2021
Posts: 472
Own Kudos [?]: 28 [0]
Given Kudos: 5901
Location: United Kingdom
Re: If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4 [#permalink]
Hello experts, why B is not sufficient? When substitute t=-5 and we can get z <0.6. Am I missing something?
Non-Human User
Joined: 09 Sep 2013
Posts: 34040
Own Kudos [?]: 853 [0]
Given Kudos: 0
Re: If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4 [#permalink]
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Re: If zt < -3, is z < 4 ? (1) z < 9 (2) t < -4 [#permalink]
Moderator:
Math Expert
94441 posts