Author 
Message 
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 50001

Is zp negative?
[#permalink]
Show Tags
25 Oct 2015, 09:13
Question Stats:
74% (01:36) correct 26% (01:23) wrong based on 1499 sessions
HideShow timer Statistics




CEO
Joined: 08 Jul 2010
Posts: 2548
Location: India
GMAT: INSIGHT
WE: Education (Education)

Re: Is zp negative?
[#permalink]
Show Tags
26 Oct 2015, 06:14
Bunuel wrote: Is zp negative?
(1) pz^4 < 0 (2) p + z^4 = 14
Kudos for a correct solution. Question : Is zp negative?Statement 1: pz^4 < 0i.e. p is Negative because z^4 must be positive for given Inequation But since the sign of z is still unknown hence, NOT SUFFICIENT Statement 2: p + z^4 = 14As per this inequation p and z can have any sign positive or negative hence nothing can be concluded NOT SUFFICIENT Combining the two statementsp is Negative but even after combining the two statement we can't conclude the sign of z. Hence, NOT SUFFICIENT Answer: Option E
_________________
Prosper!!! GMATinsight Bhoopendra Singh and Dr.Sushma Jha email: info@GMATinsight.com I Call us : +919999687183 / 9891333772 Online OneonOne Skype based classes and Classroom Coaching in South and West Delhi http://www.GMATinsight.com/testimonials.html
ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION




Current Student
Joined: 20 Mar 2014
Posts: 2633
Concentration: Finance, Strategy
GPA: 3.7
WE: Engineering (Aerospace and Defense)

Re: Is zp negative?
[#permalink]
Show Tags
25 Oct 2015, 09:47
Bunuel wrote: Is zp negative?
(1) pz^4 < 0 (2) p + z^4 = 14
Kudos for a correct solution. zp<0 ? Per statement 1, pz^4<0 > not sufficient, p=1, z=4 or p=1, z=4. Per statement 2, p + z^4 = 14 > p=13, z=1 gives you a "yes" but p=3, z^4 = 11, not sufficient, Combining, you still can not eliminate the cases raised above, making E the correct answer.



Manager
Joined: 11 Sep 2013
Posts: 110

Re: Is zp negative?
[#permalink]
Show Tags
25 Oct 2015, 09:49
Bunuel wrote: Is zp negative?
(1) pz^4 < 0 (2) p + z^4 = 14
Kudos for a correct solution. (1) pz^4 < 0 => p<0 but we do not know the sign of z => Do not know the sign of pz => Insufficient (2) p + z^4 = 14 We do not know the sign of both p and z => Insufficient (1) + (2): insufficient Ans: E



Intern
Joined: 02 Jan 2014
Posts: 39

Re: Is zp negative?
[#permalink]
Show Tags
26 Oct 2015, 01:28
Answer is E
Explaination: Question asks, Is zp <0 ?
Considering statement (1) pz^4 < 0 , as z has even power we cannot say anything about whether z is + or . It follows BCE.
Now consider statement (2) p + z^4 = 14, => p=14z^4, now this leads us to options p can be + or negative based on z's values. For example, p=1416 is 2 and p=141^4 is 13.
Even combining both of them does not provide any solution so I go for option E.



Manager
Joined: 22 Feb 2015
Posts: 56
Location: United States
Concentration: Finance, Operations
GMAT Date: 04012015
GPA: 3.98

Re: Is zp negative?
[#permalink]
Show Tags
26 Oct 2015, 04:57
Is zp negative? (1) pz^4 < 0 (2) p + z^4 = 14 Sol. zp is negative when either z or p is negative 1) pz^4 <0 so z^4 is always +ve sp p is ve but we dont know anything about z so insufficient 2) p + z^4 = 14 Dont know anything about p and z so insufficient 1) + 2) p(14p) <0 either p <0 or 14  p <0 or p >14 so noot sufficient E must be the correct answer
_________________
Click +1 KUDOS , You can make me happy with just one click! Thanks



Manager
Joined: 13 Feb 2011
Posts: 89

Is zp negative?
[#permalink]
Show Tags
26 Dec 2015, 19:00
In order for \(zp<0\), only one out of z and p must be negative and not both.
Statement 1 tells that \(p<0\) but nothing about z (as \(z^4\) will always be positive whether z is positive or negative). Hence, insufficient. Statement 2 doesn't tells anything about the signs of p and z as they could be either positive or negative to get a sum of 14. Hence, insufficient.
Combining both statements, we know that \(p<0\) and \(p+z^4=14\), that only helps us to conclude that \(z^4>14\), which again doesn't helps in confirming the sign of z (i.e. whether it's positive or negative). Hence, insufficient.
Answer: E
Hope it helps.



Intern
Joined: 18 Jan 2017
Posts: 36

Re: Is zp negative?
[#permalink]
Show Tags
21 Jan 2017, 10:27
The main issue is that even with both the statements, we still don't know the sign of "z". It can be either positive or negative. Hence, we cannot say for sure whether zp <0.



Manager
Joined: 05 Dec 2016
Posts: 246
Concentration: Strategy, Finance

Re: Is zp negative?
[#permalink]
Show Tags
16 Feb 2017, 04:00
Playing around with different signs of z we get different signs of pz, thus E.



CEO
Joined: 12 Sep 2015
Posts: 3012
Location: Canada

Re: Is zp negative?
[#permalink]
Show Tags
03 Aug 2017, 14:12
Bunuel wrote: Is zp negative?
(1) pz^4 < 0 (2) p + z^4 = 14
Kudos for a correct solution. Target question: Is zp negative? Statement 1: p(z^4) < 0 This statement doesn't FEEL sufficient, so I'll TEST some values. There are several values of p and z that satisfy statement 1. Here are two: Case a: p = 1 and z = 1. In this case, pz = (1)(1) = 1. So, pz IS negative. Case b: p = 1 and z = 1. In this case, pz = (1)(1) = 1. So, pz is NOT negative. Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: p + (z^4) = 14 There are several values of p and z that satisfy statement 1. Here are two: Case a: p = 2 and z = 2. In this case, pz = (2)(2) = 4. So, pz IS negative. Case b: p = 2 and z = 2. In this case, pz = (2)(2) = 4. So, pz is NOT negative. Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT Statements 1 and 2 combined There are still several values of p and z that satisfy BOTH statements. Here are two: Case a: p = 2 and z = 2. In this case, pz = (2)(2) = 4. So, pz IS negative. Case b: p = 2 and z = 2. In this case, pz = (2)(2) = 4. So, pz is NOT negative. Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT Answer:
_________________
Brent Hanneson – GMATPrepNow.com
Sign up for our free Question of the Day emails



Senior Manager
Joined: 16 Nov 2016
Posts: 282
WE: Advertising (Advertising and PR)

Re: Is zp negative?
[#permalink]
Show Tags
09 Jul 2018, 23:14
Hi, I don't have a copy of og16, will someone confirm whether in statement 1. only p is raised to 4 or zp is raised to 4? it looks ambiguous...i assumed it is only z^4 and got it right
_________________
If you find my post useful, please give me a kudos.
Thank you. Regards, ENEM
If you wish to spend wisely on your gmat prep material, check my post titled: How to Spend Money On GMAT Material Wisely, link: https://gmatclub.com/forum/howtobuygmatmaterialwiselytagfreegmatresources236174.html
Simple and handy template for CR: https://gmatclub.com/forum/simpleandhandytemplateforcr242255.html
simple template for more vs greater and fewer vs less: https://gmatclub.com/forum/simpletemplateformorevsgreaterandfewervsless242216.html



Math Expert
Joined: 02 Sep 2009
Posts: 50001

Re: Is zp negative?
[#permalink]
Show Tags
09 Jul 2018, 23:45



Director
Joined: 09 Mar 2016
Posts: 940

Re: Is zp negative?
[#permalink]
Show Tags
16 Aug 2018, 03:38
ENGRTOMBA2018 wrote: Bunuel wrote: Is zp negative?
(1) pz^4 < 0 (2) p + z^4 = 14
Kudos for a correct solution. zp<0 ? Per statement 1, pz^4<0 > not sufficient, p=1, z=4 or p=1, z=4. Per statement 2, p + z^4 = 14 > p=13, z=1 gives you a "yes" but p=3, z^4 = 11, not sufficient, Combining, you still can not eliminate the cases raised above, making E the correct answer. how is it possible that z^4 = 11 ? what number Z must be n this case?



Study Buddy Forum Moderator
Joined: 04 Sep 2016
Posts: 1209
Location: India
WE: Engineering (Other)

Is zp negative?
[#permalink]
Show Tags
16 Aug 2018, 06:08
dave13Here are my two cents. The question stem asks: Is either of z or p is negative But here is the catch, even if you know exact sign of p, unless you know the exact sign of z, one cannot decide whether final product will be positive or negative. If p is negative, a. but z is negative: final product is positive b. but z is positive: final product is negative. St 1 : p\(z^4\)is negative. Any number raised to even power will always be positive. But are you sure about sign of that number? \(1^4\) = 1 \((1)^4\) = 1 Hence z can be 1 or 1. Insuff All we know from this statement is that p is negative since\(z^4\) will always be positive. Coming to St 2: p + \(z^4\) = 14 Take simple values as below: 13 + \((1)^4\) = 14 13 + \((1)^4\) = 14 p is positive, z can be positive or negative You can also take (with same analogy) 2 + \((2)^4\) = 14 2 + \((2)^4\)= 14 p is negative, z can be positive or negative Combining both statements, I am still not sure about sign of z. Bottom line: z raised to even power is the culprit or trap here. Hope this helps.
_________________
It's the journey that brings us happiness not the destination.



Math Expert
Joined: 02 Sep 2009
Posts: 50001

Is zp negative?
[#permalink]
Show Tags
16 Aug 2018, 06:26
dave13 wrote: ENGRTOMBA2018 wrote: Bunuel wrote: Is zp negative?
(1) pz^4 < 0 (2) p + z^4 = 14
Kudos for a correct solution. zp<0 ? Per statement 1, pz^4<0 > not sufficient, p=1, z=4 or p=1, z=4. Per statement 2, p + z^4 = 14 > p=13, z=1 gives you a "yes" but p=3, z^4 = 11, not sufficient, Combining, you still can not eliminate the cases raised above, making E the correct answer. how is it possible that z^4 = 11 ? what number Z must be n this case? A number the fourth power of which equal to 11: \(\sqrt[4]{11}\) or \(\sqrt[4]{11}\)
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics




Is zp negative? &nbs
[#permalink]
16 Aug 2018, 06:26






