GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 13 Dec 2018, 08:26

Stanford Chat (Calls Started)  |  Wharton Chat  (Calls Expected Soon)  |  Fuqua Chat (Calls Expected Soon)

### 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

## Events & Promotions

###### Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### The winning strategy for 700+ on the GMAT

December 13, 2018

December 13, 2018

08:00 AM PST

09:00 AM PST

What people who reach the high 700's do differently? We're going to share insights, tips and strategies from data we collected on over 50,000 students who used examPAL.
• ### GMATbuster's Weekly GMAT Quant Quiz, Tomorrow, Saturday at 9 AM PST

December 14, 2018

December 14, 2018

09:00 AM PST

10:00 AM PST

10 Questions will be posted on the forum and we will post a reply in this Topic with a link to each question. There are prizes for the winners.

# M06-06

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 51185

### Show Tags

15 Sep 2014, 23:27
1
3
00:00

Difficulty:

15% (low)

Question Stats:

84% (01:10) correct 16% (01:31) wrong based on 110 sessions

### HideShow timer Statistics

If $$y(u - c) = 0$$ and $$j(u - k) = 0$$, which of the following must be true, assuming $$c \lt k$$?

A. $$yj \lt 0$$
B. $$yj \gt 0$$
C. $$yj = 0$$
D. $$j = 0$$
E. $$y = 0$$

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 51185

### Show Tags

15 Sep 2014, 23:27
1
Official Solution:

If $$y(u - c) = 0$$ and $$j(u - k) = 0$$, which of the following must be true, assuming $$c \lt k$$?

A. $$yj \lt 0$$
B. $$yj \gt 0$$
C. $$yj = 0$$
D. $$j = 0$$
E. $$y = 0$$

$$y(u - c) = 0$$. Either $$u=c$$ or $$y=0$$;

$$j(u - k) = 0$$. Either $$u=k$$ or $$j=0$$;

Now, the first option ($$u=c$$ and $$u=k$$) cannot be simultaneously correct for both equations because if it is, then it would mean that $$u=c=k$$, but we are given that $$c \lt k$$. So, only one can be correct so either $$y=0$$ or $$j=0$$, which makes $$yj = 0$$ always true.

_________________
Current Student
Joined: 18 Jun 2015
Posts: 41

### Show Tags

12 Sep 2016, 11:43
Thanks for the explanation. Somehow I missed to guess the logic of u=c and u=k can't happen simultaneously.
And got this wrong. The explanation is crisp and concise.
Intern
Joined: 01 Jan 2016
Posts: 2

### Show Tags

26 Dec 2017, 19:39
Hello Bunuel,
besides the fact that c<k, can't it be "and/or" instead of "or" for each assumption?
y(u−c)=0. Either u=c AND/or y=0? It doesn't change the answer but I would like to know why you didn't include it in your solution. Thank you
Math Expert
Joined: 02 Sep 2009
Posts: 51185

### Show Tags

26 Dec 2017, 20:01
1
Guimeister wrote:
Hello Bunuel,
besides the fact that c<k, can't it be "and/or" instead of "or" for each assumption?
y(u−c)=0. Either u=c AND/or y=0? It doesn't change the answer but I would like to know why you didn't include it in your solution. Thank you

Yes it's an inclusive OR, which means that Either $$u=c$$ or $$y=0$$ (or both).
_________________
Re: M06-06 &nbs [#permalink] 26 Dec 2017, 20:01
Display posts from previous: Sort by

# M06-06

Moderators: chetan2u, Bunuel

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.