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

It is currently 02 Aug 2014, 00:49

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

A boy finds an average of 10 positive integers. Each

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2003
Posts: 325
Location: dallas , tx
Followers: 1

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

GMAT Tests User
A boy finds an average of 10 positive integers. Each [#permalink] New post 21 Dec 2003, 11:27
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
A boy finds an average of 10 positive integers. Each integeres contain two digits .By mistake the boy interchanges the digits of one number say ba for ab. Due to this the average become 1.8 less than the previous one.What was the difference of the two digit a and b?
a)4
b)2
c)6
d)8

Any easy & understandable solution?
_________________

shubhangi

Director
Director
User avatar
Joined: 13 Nov 2003
Posts: 971
Location: Florida
Followers: 1

Kudos [?]: 13 [0], given: 0

GMAT Tests User
 [#permalink] New post 21 Dec 2003, 12:27
2 ??

here's how I did it..

suppose that the sum of 9 integers is A9
S is the average.

{A9+(10X+Y)}/10 = S

after intechanging digits;
{A9+(10Y+X)}/10 = S-1.8

subtract 2nd from 1st, u will get X-Y = 2
Intern
Intern
User avatar
Joined: 04 Oct 2003
Posts: 42
Location: Silicon Valley, CA
Followers: 0

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

 [#permalink] New post 21 Dec 2003, 14:02
dj - exellent approach. Thanks for the solution.
CEO
CEO
avatar
Joined: 15 Aug 2003
Posts: 3470
Followers: 59

Kudos [?]: 661 [0], given: 781

Re: PS [#permalink] New post 22 Dec 2003, 11:44
shubhangi wrote:
A boy finds an average of 10 positive integers. Each integeres contain two digits .By mistake the boy interchanges the digits of one number say ba for ab. Due to this the average become 1.8 less than the previous one.What was the difference of the two digit a and b?
a)4
b)2
c)6
d)8

Any easy & understandable solution?


let the number be represented by 10a + b
a = tens digits
b = unit digit
we know that.
Orginal Average - Mistaken Average = 1.8
[(Sum of 9 nos.) + (10 a+b) / 10] - [Sum of 9 nos +(10b +a) / 10]= 1.8

that is just...

[(10a + b ) - (10b +a)] /10 =1.8 ( 10 is the common denominator..so
we can simplify)
10a + b -10b -a = 18
9a - 9b =18

thus,
a- b =2

recall a = tenths digits, b =units digits

Answer B
Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2003
Posts: 325
Location: dallas , tx
Followers: 1

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

GMAT Tests User
 [#permalink] New post 22 Dec 2003, 14:42
Yuppy!!
2 is right.
thanks both of you .. praet and dj.
_________________

shubhangi

  [#permalink] 22 Dec 2003, 14:42
    Similar topics Author Replies Last post
Similar
Topics:
1 Experts publish their posts in the topic x, y, and z are three positive integers whose average is 10 WoundedTiger 2 29 Jan 2014, 04:01
11 Experts publish their posts in the topic S is a set of positive integers. The average of the terms in rohitgarg 14 23 Sep 2012, 19:27
5 Experts publish their posts in the topic If the average of 5 positive integers is 40 and the nafishasan60 3 04 Feb 2012, 03:15
If the average of positive integers x, y, and z is 10, what arjtryarjtry 4 25 Jul 2008, 02:45
Three positive integers: m. n and q, their average is 10, blog 10 03 Feb 2008, 00:10
Display posts from previous: Sort by

A boy finds an average of 10 positive integers. Each

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

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®.