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

It is currently 26 Nov 2014, 15:04

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

What is the sum of the first 50 common numbers between the

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 11 Dec 2003
Posts: 49
Location: IN
Followers: 1

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

What is the sum of the first 50 common numbers between the [#permalink] New post 13 Apr 2005, 14:21
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
What is the sum of the first 50 common numbers between the series 15,19,23....... and 14,19,24.........?

A) 25550
B) 24540
C) 24450
D) 25450
E) 25540
VP
VP
User avatar
Joined: 25 Nov 2004
Posts: 1497
Followers: 6

Kudos [?]: 33 [0], given: 0

Re: PS old qn. [#permalink] New post 13 Apr 2005, 19:45
D) 25450

Series I: 15,19,23,27,31,35,39,43,47,51,55,59................................
Series II: 14,19,24,29,34,39, 44,49,54,59........................................

The common numbers are 19, 39,59. Note here the pattren, 19-39-59: the difference between two sucessive common numbers is 20.
the last common number is =19+(49x20)=999
the average of the 50 common numbers = (19+999)/2=509
sum = 509x50=25450. will correct if any and this is the shortest method i have.
Intern
Intern
avatar
Joined: 11 Dec 2003
Posts: 49
Location: IN
Followers: 1

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

 [#permalink] New post 14 Apr 2005, 05:57
MA Thanks a lot for the expln.

"the last common number is =19+(49x20)=999"

How did you get 49 here there are 50 numbers ? Could you please explain this part alone. Rest is clear.
VP
VP
avatar
Joined: 18 Nov 2004
Posts: 1447
Followers: 2

Kudos [?]: 18 [0], given: 0

 [#permalink] New post 14 Apr 2005, 07:49
"B"

remember this formula for summation of equally spaced numbers

S = n/2 ((2a + (n-1)*d)

n = number of elements (50 here)
a = first element (19 here)
d = difference between successive elements (20 here)

S = 50/2 (38 + 49*20)

S = 25450
Senior Manager
Senior Manager
avatar
Joined: 19 Feb 2005
Posts: 488
Location: Milan Italy
Followers: 1

Kudos [?]: 9 [0], given: 0

 [#permalink] New post 14 Apr 2005, 09:06
Hey guys, look at this:
MA said
Series I: 15,19,23,27,31,35,39,43,47,51,55,59................................
Series II: 14,19,24,29,34,39, 44,49,54,59........................................
the difference between two sucessive common numbers is 20

this is 4*5 (note that there are no common factors bw the two numb)

If I say
Series I: 16,19,22,25,28,31,34,37,40,43,46,49................................
Series II: 12,19,26,33,40,47, 54,61,68,75........................................
the difference between two sucessive common numbers is 21

this is 3*7

this is something I can't explain, but my bells rang and I just shared their sound with you :-D
VP
VP
User avatar
Joined: 25 Nov 2004
Posts: 1497
Followers: 6

Kudos [?]: 33 [0], given: 0

 [#permalink] New post 14 Apr 2005, 16:48
TS wrote:
How did you get 49 here there are 50 numbers ? Could you please explain this part alone. Rest is clear.


you forget to count first one i.e. 19.
the first one is 19 and rest are 49 numbers, total 50.
  [#permalink] 14 Apr 2005, 16:48
    Similar topics Author Replies Last post
Similar
Topics:
2 Experts publish their posts in the topic What is the sum of all 50 numbers in a list? brunora 1 04 Sep 2014, 15:53
The sum of the first 50 positive even integers is 2550. what enola 4 12 Dec 2006, 05:54
What is the sum of the first 50 common numbers between the yezz 3 12 Oct 2006, 15:43
What is the difference between the sum of the numbers from 1 Rayn 4 12 Oct 2006, 12:36
The sum of the first 50 positive even integers is 2550. What Matador 4 15 Apr 2006, 13:37
Display posts from previous: Sort by

What is the sum of the first 50 common numbers between the

  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®.