Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 06 May 2015, 21:14

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 June
Open Detailed Calendar

If x^4+y^4=100, then the greatest possible value of x is

 Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Manager
Joined: 28 Jul 2004
Posts: 136
Location: Melbourne
Schools: Yale SOM, Tuck, Ross, IESE, HEC, Johnson, Booth
Followers: 1

Kudos [?]: 21 [0], given: 2

If x^4+y^4=100, then the greatest possible value of x is [#permalink]  23 Aug 2008, 03:22
1
This post was
BOOKMARKED
00:00

Difficulty:

45% (medium)

Question Stats:

61% (01:40) correct 39% (00:55) wrong based on 171 sessions
If x^4+y^4=100, then the greatest possible value of x is between

A. 0 and 3
B. 3 and 6
C. 6 and 9
D. 9 and 12
E. 12 and 15

OPEN DISCUSSION OF THIS QUESTION IS HERE: if-x-4-y-4-100-then-the-greatest-possible-value-of-x-is-128171.html
[Reveal] Spoiler: OA

_________________

kris

Last edited by Bunuel on 19 Jul 2013, 01:54, edited 2 times in total.
Renamed the topic, edited the question, added the OA and moved to PS forum.
 Kaplan Promo Code Knewton GMAT Discount Codes Manhattan GMAT Discount Codes
SVP
Joined: 07 Nov 2007
Posts: 1828
Location: New York
Followers: 29

Kudos [?]: 542 [0], given: 5

Re: Greatest Possible values of x? [#permalink]  23 Aug 2008, 03:41
krishan wrote:
If x4 + y4 = 100 then the greatest possible value of x is between:

a) 0 and 3
b) 3 and 6
c) 6 and 9
d) 9 and 12
e) 12 and 15

x4 is x raised to the power of 4 (I could not figure out how to show it as an exponent)

Thanks

Greatest possible value of X when Y^4 is minimum.
The possible minimum value of Y^4 is 0
$$X^4=100 ---> X^2=10 --> X> 3 AND X<4$$
B is the answer.
_________________

Smiling wins more friends than frowning

Manager
Joined: 28 Jul 2004
Posts: 136
Location: Melbourne
Schools: Yale SOM, Tuck, Ross, IESE, HEC, Johnson, Booth
Followers: 1

Kudos [?]: 21 [0], given: 2

Re: Greatest Possible values of x? [#permalink]  23 Aug 2008, 04:32
Thanks a lot Suresh.
_________________

kris

Manager
Joined: 20 May 2008
Posts: 57
Followers: 2

Kudos [?]: 5 [0], given: 1

Re: Greatest Possible values of x? [#permalink]  23 Aug 2008, 23:09
shailyam,
The ans should be B not A since values geater than 3 also satify the equation e.g. x = 3.1 can also be possible.
Intern
Joined: 07 Jul 2013
Posts: 7
Followers: 0

Kudos [?]: 4 [0], given: 2

Re: Greatest Possible values of x? [#permalink]  19 Jul 2013, 01:00
LoyalWater wrote:
shailyam,
The ans should be B not A since values geater than 3 also satify the equation e.g. x = 3.1 can also be possible.

Going by your logic, one can consider 3.1 as a possible value of x. Here we're not sure of the value of x and saying that the greatest possible value of x is between 3 and 6 would mean that x could be even more than 3.1, for example 4. Hence, answer is A
Math Expert
Joined: 02 Sep 2009
Posts: 27238
Followers: 4237

Kudos [?]: 41166 [2] , given: 5672

Re: Greatest Possible values of x? [#permalink]  19 Jul 2013, 01:54
2
KUDOS
Expert's post
kshitij90 wrote:
LoyalWater wrote:
shailyam,
The ans should be B not A since values geater than 3 also satify the equation e.g. x = 3.1 can also be possible.

Going by your logic, one can consider 3.1 as a possible value of x. Here we're not sure of the value of x and saying that the greatest possible value of x is between 3 and 6 would mean that x could be even more than 3.1, for example 4. Hence, answer is A

That's not correct.

If x^4+y^4=100, then the greatest possible value of x is between

A. 0 and 3
B. 3 and 6
C. 6 and 9
D. 9 and 12
E. 12 and 15

General rule for such kind of problems:
to maximize one quantity, minimize the others;
to minimize one quantity, maximize the others.

So, to maximize $$x$$ we should minimize $$y^4$$. Least value of $$y^4$$ is zero. In this case $$x^4+0=100$$ --> $$x^4=100$$ --> $$x^2=10$$ --> $$x=\sqrt{10}\approx{3.2}$$, which is in the range (3,6).

Hope it's clear.

OPEN DISCUSSION OF THIS QUESTION IS HERE: if-x-4-y-4-100-then-the-greatest-possible-value-of-x-is-128171.html
_________________
Re: Greatest Possible values of x?   [#permalink] 19 Jul 2013, 01:54
Similar topics Replies Last post
Similar
Topics:
1 What is the greatest possible value of x ? 4 26 Oct 2014, 01:32
7 what is the greatest possible value of the function f(x)? 5 07 Apr 2014, 02:47
If X^4+Y^4=100, then the greatest possible value of X is 3 05 Jun 2007, 10:58
If x^4+y^4=100, then the greatest possible value of x is 2 03 Dec 2006, 05:37
1 If x^4 + y^4 = 100, then the greatest possible value of x is 28 23 Oct 2005, 10:15
Display posts from previous: Sort by

If x^4+y^4=100, then the greatest possible value of x is

 Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group and phpBB SEO 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®.