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

It is currently 22 Sep 2014, 10:55

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

The sum of positive integers x and y is 77. What is value of

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 08 Nov 2006
Posts: 36
Followers: 0

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

The sum of positive integers x and y is 77. What is value of [#permalink] New post 08 Nov 2006, 10:14
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

63% (01:52) correct 37% (00:40) wrong based on 202 sessions
The sum of positive integers x and y is 77. What is value of xy?

(1) x = y + 1
(2) x and y have the same tens digit.

[Reveal] Spoiler:
I answered that "statement 1 alone is sufficient, but statement 2 alone is not sufficient.

The test said that each statement alone is sufficient.

How can this be? If X = 32 and Y = 35, then XY = 1120 but if X= 33 and Y = 34, then XY = 1122. They have the same 10's digit in each case, but not the same product.

Am I missing something obvious or is the answer wrong in gmatprep?

Thanks,

Andrew
[Reveal] Spoiler: OA

Last edited by Bunuel on 20 Aug 2013, 08:52, edited 1 time in total.
Renamed the topic, edited the question, added the OA and moved to DS forum.
Kaplan GMAT Prep Discount CodesKnewton GMAT Discount CodesGMAT Pill GMAT Discount Codes
2 KUDOS received
Manager
Manager
User avatar
Joined: 03 Nov 2006
Posts: 161
Followers: 2

Kudos [?]: 3 [2] , given: 0

Re: The sum of positive integers X and Y is 77. What is xy? [#permalink] New post 08 Nov 2006, 10:23
2
This post received
KUDOS
andrewnorway wrote:
Can someone explain this to me, its a data suff problem:

The sum of positive integers X and Y is 77. What is value of xy?

(1) X = Y+1

(2) X and Y have the same tens digit


I answered that "statement 1 alone is sufficient, but statement 2 alone is not sufficient.

The test said that each statement alone is sufficient.

How can this be? If X = 32 and Y = 35, then XY = 1120 but if X= 33 and Y = 34, then XY = 1122. They have the same 10's digit in each case, but not the same product.

Am I missing something obvious or is the answer wrong in gmatprep?

Thanks,

Andrew


32+35 is not equal to 77

There are only 2 numbers that add up to 77 and have the same 10 digits. They are 38 and 39. Therefore either statement is sufficient - D
Intern
Intern
avatar
Joined: 08 Nov 2006
Posts: 36
Followers: 0

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

wow [#permalink] New post 08 Nov 2006, 10:28
I really should have looked at that one again before posting :-). thanks.
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 07 Jul 2004
Posts: 5097
Location: Singapore
Followers: 19

Kudos [?]: 145 [0], given: 0

GMAT Tests User
 [#permalink] New post 08 Nov 2006, 17:14
St1:
x = y+1
so y+1+y = 77 --> can solve for y, then can solve for x and finally xy. Sufficient.

st2:
x and y have the same tens digit. We can rule out the tens digit 1,2,4,5-9 because that would require the other integer to take either a bigger or smaller value. The only value that works is 38,39. Since it's multiplication, we don't care if x took 38 or x took 39. xy will be the same. Sufficient.

Ans D
Intern
Intern
avatar
Joined: 20 Aug 2013
Posts: 11
Location: United States
Concentration: Marketing, Strategy
GMAT 1: 720 Q38 V41
WE: Project Management (Consulting)
Followers: 0

Kudos [?]: 5 [0], given: 3

Re: The sum of positive integers X and Y is 77. What is xy? [#permalink] New post 20 Aug 2013, 08:48
The question says that X and Y are two positive integers but solving statement 1 you will get X and Y as fractions. If the statement refutes the question data then what is the answer?
Expert Post
4 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23509
Followers: 3515

Kudos [?]: 26674 [4] , given: 2714

Re: The sum of positive integers X and Y is 77. What is xy? [#permalink] New post 20 Aug 2013, 08:58
4
This post received
KUDOS
Expert's post
1
This post was
BOOKMARKED
spjmanoli wrote:
The question says that X and Y are two positive integers but solving statement 1 you will get X and Y as fractions. If the statement refutes the question data then what is the answer?


Actually we don't get fractions.

The sum of positive integers x and y is 77. What is value of xy?

Given that x+y=77 find the value of xy.

(1) x = y + 1 --> (y+1)+y=77 --> y=38 and x=39 --> xy=39*38. Sufficient.

(2) x and y have the same tens digit. In order the sum to be 77 the tens digit of of x and y must be 3, thus x=38 and y=39 or vise-versa, in either case xy=39*38. Sufficient.

Answer: D.

Hope this helps.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Director
Director
avatar
Joined: 17 Apr 2013
Posts: 530
Concentration: Entrepreneurship, Leadership
Schools: HBS '16
GMAT Date: 11-30-2013
GPA: 3.3
Followers: 3

Kudos [?]: 39 [0], given: 246

CAT Tests
Re: The sum of positive integers X and Y is 77. What is xy? [#permalink] New post 24 Sep 2013, 01:46
Bunuel wrote:
spjmanoli wrote:
The question says that X and Y are two positive integers but solving statement 1 you will get X and Y as fractions. If the statement refutes the question data then what is the answer?


Actually we don't get fractions.

The sum of positive integers x and y is 77. What is value of xy?

Given that x+y=77 find the value of xy.

(1) x = y + 1 --> (y+1)+y=77 --> y=38 and x=39 --> xy=39*38. Sufficient.

(2) x and y have the same tens digit. In order the sum to be 77 the tens digit of of x and y must be 3, thus x=38 and y=39 or vise-versa, in either case xy=39*38. Sufficient.

Answer: D.

Hope this helps.


Questions says 10's digit same, but isn't it assumption that it should be 3? Like this we can assume anything and solve the question.
_________________

Like my post Send me a Kudos :) It is a Good manner.

Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23509
Followers: 3515

Kudos [?]: 26674 [1] , given: 2714

Re: The sum of positive integers X and Y is 77. What is xy? [#permalink] New post 24 Sep 2013, 01:52
1
This post received
KUDOS
Expert's post
honchos wrote:
Bunuel wrote:
spjmanoli wrote:
The question says that X and Y are two positive integers but solving statement 1 you will get X and Y as fractions. If the statement refutes the question data then what is the answer?


Actually we don't get fractions.

The sum of positive integers x and y is 77. What is value of xy?

Given that x+y=77 find the value of xy.

(1) x = y + 1 --> (y+1)+y=77 --> y=38 and x=39 --> xy=39*38. Sufficient.

(2) x and y have the same tens digit. In order the sum to be 77 the tens digit of of x and y must be 3, thus x=38 and y=39 or vise-versa, in either case xy=39*38. Sufficient.

Answer: D.

Hope this helps.


Questions says 10's digit same, but isn't it assumption that it should be 3? Like this we can assume anything and solve the question.


No. The tens digit of x and y cannot be any digit but 3: if it's less than 3, then x+y<77 and if it's greater than 3 then x+y>77.

Does this make sense?
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
avatar
Joined: 06 Aug 2011
Posts: 409
Followers: 2

Kudos [?]: 60 [0], given: 82

Re: The sum of positive integers x and y is 77. What is value of [#permalink] New post 13 Feb 2014, 23:28
Nice question !

X+y=77

x=y+1

then x=39 and y=38 statement 1 is sufficient

statement 2---> same tens digit means both numbers are from 30 to 39 inclusive. so there is only two digits 38 and 39. sufficient

if it wud have been less 77.. for example 76 or 75..x+y=75 or x+y=76 then statement 2 wud have been insuffient. A trick is they have given 77..if we jump one number tens digit wud be 4.
_________________

Bole So Nehal.. Sat Siri Akal.. Waheguru ji help me to get 700+ score !

Re: The sum of positive integers x and y is 77. What is value of   [#permalink] 13 Feb 2014, 23:28
    Similar topics Author Replies Last post
Similar
Topics:
The sum of positive integers x and y is 77. What is value of tarek99 1 17 Aug 2008, 22:04
The sum of positive integers x and y is 77. What is the agold 5 26 Jun 2008, 14:28
The sum of positive integers x and y is 77. What is the mbunny 7 03 Sep 2007, 17:09
The sum of positive integers x and y is 77 What is the value joemama142000 11 07 Dec 2005, 19:35
The sum of positive integers x and y is 77. what is the trickygmat 9 17 Oct 2005, 13:10
Display posts from previous: Sort by

The sum of positive integers x and y is 77. What is value of

  Question banks Downloads My Bookmarks Reviews Important topics  


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

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®.