Last visit was: 11 Dec 2024, 05:49 It is currently 11 Dec 2024, 05:49
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
shubhangi
Joined: 30 Aug 2003
Last visit: 26 Aug 2004
Posts: 183
Own Kudos:
Location: dallas , tx
Posts: 183
Kudos: 173
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
dj
Joined: 13 Nov 2003
Last visit: 25 Jun 2012
Posts: 558
Own Kudos:
Location: Florida
Posts: 558
Kudos: 1,000
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
bat_car
Joined: 04 Oct 2003
Last visit: 21 Feb 2004
Posts: 25
Own Kudos:
Location: Silicon Valley, CA
Posts: 25
Kudos: 3
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Praetorian
Joined: 15 Aug 2003
Last visit: 27 Dec 2017
Posts: 2,876
Own Kudos:
Given Kudos: 781
Posts: 2,876
Kudos: 1,669
Kudos
Add Kudos
Bookmarks
Bookmark this Post
shubhangi
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
User avatar
shubhangi
Joined: 30 Aug 2003
Last visit: 26 Aug 2004
Posts: 183
Own Kudos:
Location: dallas , tx
Posts: 183
Kudos: 173
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Yuppy!!
2 is right.
thanks both of you .. praet and dj.



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Problem Solving (PS) Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
Moderators:
Math Expert
97803 posts
Senior Moderator - Masters Forum
3116 posts