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

It is currently 25 Jun 2018, 08:21

Close

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
Your Progress

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

2 KUDOS received
Intern
Intern
avatar
Joined: 24 Jan 2017
Posts: 3
If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then [#permalink]

Show Tags

New post Updated on: 15 Feb 2017, 12:14
2
3
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

60% (01:05) correct 40% (01:19) wrong based on 104 sessions

HideShow timer Statistics

If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is

(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200

Originally posted by lgarces19 on 15 Feb 2017, 12:08.
Last edited by Bunuel on 15 Feb 2017, 12:14, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 46303
Re: If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then [#permalink]

Show Tags

New post 15 Feb 2017, 12:17
lgarces19 wrote:
If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is

(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200


Square k + m = 20;

(k + m)^2 = 20^2;

k^2 + 2km + m^2 = 400.

Since given that k^2 + m^2 = 289, then 289 + 2km = 400.

km = 111/2 = 55.5.

Answer: A.

P.S. Is this question really from GMAT Prep?
_________________

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?
Extra-hard Quant Tests with Brilliant Analytics

Board of Directors
User avatar
P
Joined: 17 Jul 2014
Posts: 2729
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge
Re: If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then [#permalink]

Show Tags

New post 15 Feb 2017, 14:47
Bunuel wrote:
lgarces19 wrote:
If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is

(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200


Square k + m = 20;

(k + m)^2 = 20^2;

k^2 + 2km + m^2 = 400.

Since given that k^2 + m^2 = 289, then 289 + 2km = 400.

km = 111/2 = 55.5.

Answer: A.

P.S. Is this question really from GMAT Prep?



clearly, I need to brush up my quant skills...I took into consideration that k and m are integers...damn!
Expert Post
Top Contributor
1 KUDOS received
CEO
CEO
User avatar
P
Joined: 12 Sep 2015
Posts: 2597
Location: Canada
Re: If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then [#permalink]

Show Tags

New post 16 Feb 2017, 10:31
1
Top Contributor
lgarces19 wrote:
If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is

(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200


Bunuel's solution is perfect.
I just want to point out that there's no shortage of questions that test the concepts tested here.

Important expansions: (x + y)² = x² + 2xy + y² and (x - y)² = x² - 2xy + y²
So, if you see questions that include information about x² + y² and 2xy (or just xy), then you should consider their relationship with the above expansions.

Cheers,
Brent
_________________

Brent Hanneson – Founder of gmatprepnow.com

Image

Board of Directors
User avatar
G
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3513
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)
GMAT ToolKit User Premium Member
Re: If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then [#permalink]

Show Tags

New post 16 Feb 2017, 11:57
lgarces19 wrote:
If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then the value of the product km is

(A) between 20 and 60
(B) between 60 and 100
(C) between 100 and 150
(D) between 150 and 200
(E) greater than 200


\(( k + m ) ^2= k^2 + m^2 + 2km\)

So, \(( 20 ) ^2= 289 + 2km\)

Or, \(400 = 289 + 2km\)

Or, \(2km = 111\)

Or, \(km = 55.5\)

Thus, km must be between 20 and 60, answer must be option (A) between 20 and 60
_________________

Thanks and Regards

Abhishek....

PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS

How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only )

Re: If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then   [#permalink] 16 Feb 2017, 11:57
Display posts from previous: Sort by

If k and m are numbers such that k + m = 20 and k^2 + m^2 = 289, then

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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®.