If, (x^2 + 8)yz < 0, wz> 0 and xyz<0 then which of

Expert replies

GMATinsight: Legendary Member; Posts: 1100; Joined: Sat May 10, 2014 11:34 pmFollowed by: 24 members; Location: New Delhi, India; Thanked: 205 times

by GMATinsight » Wed Oct 14, 2015 8:55 am

If, (x^2 + 8)yz < 0, wz> 0 and xyz<0 then which of the following must be true?

(I) x < 0
(II) wy < 0
(III) yz < 0

(A)II only
(B)III only
(C)I and III only
(D)II and III only
(E)I, II and III all

Answer: Option D

Last edited by GMATinsight on Thu Oct 15, 2015 2:11 am, edited 1 time in total.

"GMATinsight"Bhoopendra Singh & Sushma Jha
Most Comprehensive and Affordable Video Course 2000+ CONCEPT Videos and Video Solutions
Whatsapp/Mobile: +91-9999687183 l [email protected]
Contact for One-on-One FREE ONLINE DEMO Class Call/e-mail
Most Efficient and affordable One-On-One Private tutoring fee - US$40-50 per hour

Like this post

Source: Beat The GMAT — Problem Solving | Wed Oct 14, 2015 8:55 am

GMATinsight: Legendary Member; Posts: 1100; Joined: Sat May 10, 2014 11:34 pmFollowed by: 24 members; Location: New Delhi, India; Thanked: 205 times

by GMATinsight » Wed Oct 14, 2015 8:56 am

GMATinsight wrote:If, (x^2 + 8)yz < 0, wz> 0 and xyz<0 then which of the following must be true?

(I) x < 0
(II) wy < 0
(III) yz < 0

(A)II only
(B)III only
(C)I and III only
(D)II and III only
(E)I, II and III all

Answer: Option D

(x^2 + 8)yz < 0
(x^2 + 8) must be positive (greater than or equal to 8 as x^2 can't be Negative)
i.e. yz < 0
i.e. y and z have opposite signs (One of y and z is Negative and other is positive)

wz> 0
i.e. w and z have Same signs (Both Positive or Both Negative)

xyz < 0
Since yz is Negative so x must be Positive

also If w and z are Negative then y is Positive or Vice Versa

(I) x < 0 is Definitely Incorrect
(II) wy < 0 is CORRECT as w and y have opposite signs
(III) yz < 0 is CORRECT

Answer: option D

Last edited by GMATinsight on Thu Oct 15, 2015 2:12 am, edited 1 time in total.

Like this post

Matt@VeritasPrep: GMAT Instructor; Posts: 2630; Joined: Wed Sep 12, 2012 3:32 pmFollowed by: 119 members; Location: East Bay all the way; Thanked: 625 times; GMAT Score:780

by Matt@VeritasPrep » Thu Oct 15, 2015 12:13 am

Strictly speaking, (III) isn't quite correct. yz < 0 is a consequence of (xÂ² + 8)*yz < 0 ... it has nothing to do with the sign of w.

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

559 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review