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

It is currently 23 Jul 2014, 04:06

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 range of a set consisting of the first 100 multi

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Director
Director
avatar
Joined: 10 Feb 2006
Posts: 664
Followers: 1

Kudos [?]: 32 [0], given: 0

GMAT Tests User
What is the range of a set consisting of the first 100 multi [#permalink] New post 21 Jun 2008, 19:08
2
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

58% (02:03) correct 42% (00:49) wrong based on 79 sessions
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?

A. 693
B. 700
C. 707
D. 777
E. 847
[Reveal] Spoiler: OA

_________________

GMAT the final frontie!!!.


Last edited by Bunuel on 14 Jan 2014, 23:49, edited 1 time in total.
Renamed the topic, edited the question, added the OA and moved to PS forum.
Director
Director
avatar
Joined: 23 Sep 2007
Posts: 798
Followers: 5

Kudos [?]: 73 [0], given: 0

GMAT Tests User
Re: Range [#permalink] New post 21 Jun 2008, 19:16
A
the first 100 multiples of 7 is 7-700, so the range is 693

It does not matter if you start at 7 or 77
1 KUDOS received
Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 2049
Followers: 125

Kudos [?]: 874 [1] , given: 376

GMAT Tests User
Re: range [#permalink] New post 23 Mar 2011, 21:28
1
This post received
KUDOS
AnkitK wrote:
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?

A.693
B.700
C.707
D.777
E.847


a_1=77
a_{100}=77+(99)*7=693+77

Range = 693+77-77=693

Ans: "A"

_________________

~fluke

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Senior Manager
Senior Manager
avatar
Joined: 12 Oct 2009
Posts: 272
Schools: Columbia, INSEAD, RSM, LBS
Followers: 2

Kudos [?]: 29 [0], given: 4

GMAT Tests User
Re: range [#permalink] New post 09 Apr 2011, 10:08
First Multiple greater than 70 -> 7 * 11 = 77
100th Multiple greater than 70 -> 7 * (11+100) = 770

Range is 770-77 = 693....

Pls can somebody explain where I am making a mistake and why is the answer 777 and not 693
Expert Post
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4566
Location: Pune, India
Followers: 1029

Kudos [?]: 4455 [0], given: 162

Re: range [#permalink] New post 09 Apr 2011, 20:12
Expert's post
IEsailor wrote:
First Multiple greater than 70 -> 7 * 11 = 77
100th Multiple greater than 70 -> 7 * (11+100) = 770

Range is 770-77 = 693....

Pls can somebody explain where I am making a mistake and why is the answer 777 and not 693


There are a couple of mistakes you made but they canceled out to give the right answer! (693 is the right answer)

100th multiple greater than 70 will be 7 (10 + 100) or we can say 70 + 7*100 because it has to be the 100th multiple after 70.
When you do 7 * (11+100) i.e. 77 + 7*100, you are calculating the 101th multiple since you are finding the 100th multiple after 77, not 70.

The second error is that 7 * (11+100) = 777, not 770
Actually, 7 (10 + 100) = 770

The range is 770 - 77 = 693

_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Senior Manager
Senior Manager
avatar
Status: ready to boMBArd
Joined: 31 Oct 2010
Posts: 494
Location: India
Concentration: Entrepreneurship, Strategy
GMAT 1: 710 Q48 V40
WE: Project Management (Manufacturing)
Followers: 13

Kudos [?]: 31 [0], given: 74

CAT Tests
Re: range [#permalink] New post 10 Apr 2011, 09:31
First multiple of 7 after 70= 77
100th multiple of 7 after 70= 110th multiple of 7= 770

Range= 100th multiple-first multiple= 770-77= 693.

Ans: A.

Ankitk, could you please check whether you've posted the correct OA? Thanks.

_________________

My GMAT debrief: from-620-to-710-my-gmat-journey-114437.html

Director
Director
avatar
Joined: 01 Feb 2011
Posts: 770
Followers: 14

Kudos [?]: 80 [0], given: 42

GMAT Tests User
Re: range [#permalink] New post 10 Apr 2011, 10:36
sequence is as follows.

77,84,....770

Range = 770-77 = 693

Answer A.
1 KUDOS received
Intern
Intern
avatar
Joined: 01 Oct 2010
Posts: 20
Schools: Ross,Duke,Emory
Followers: 0

Kudos [?]: 2 [1] , given: 5

Re: range [#permalink] New post 11 Apr 2011, 11:11
1
This post received
KUDOS
100 multiples of 7 greater than 70 will be as follows :

77+84+91+...

= 7 ( 11 + 12 + 13 + .....+110 )

so the last term is 770.

Range = 770 - 77 = 693.

Ans : A
Director
Director
User avatar
Status: GMAT Learner
Joined: 14 Jul 2010
Posts: 653
Followers: 32

Kudos [?]: 191 [0], given: 32

GMAT Tests User
Re: range [#permalink] New post 13 Apr 2011, 06:49
fluke wrote:
AnkitK wrote:
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?

A.693
B.700
C.707
D.777
E.847


a_1=77
a_{100}=77+(99)*7=693+77

Range = 693+77-77=693

Ans: "A"


why is 99 is multiplied by 7?

_________________

I am student of everyone-baten
Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

1 KUDOS received
Math Forum Moderator
avatar
Joined: 20 Dec 2010
Posts: 2049
Followers: 125

Kudos [?]: 874 [1] , given: 376

GMAT Tests User
Re: range [#permalink] New post 13 Apr 2011, 06:59
1
This post received
KUDOS
Baten80 wrote:
fluke wrote:
AnkitK wrote:
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?

A.693
B.700
C.707
D.777
E.847


a_1=77
a_{100}=77+(99)*7=693+77

Range = 693+77-77=693

Ans: "A"


why is 99 is multiplied by 7?


In an arithmetic progression
A_n=A_1+(n-1)*d

{77,84,91,98,.....,}
A_1=First \hspace{2} term=77
d=Common \hspace{2} Difference=7

A_{100}=A_1+(n-1)*d
A_{100}=77+(100-1)*7
A_{100}=77+99*7
A_{100}-A_1=77+99*7-77=99*7

_________________

~fluke

Get the best GMAT Prep Resources with GMAT Club Premium Membership

2 KUDOS received
GMAT Instructor
avatar
Joined: 24 Jun 2008
Posts: 967
Location: Toronto
Followers: 246

Kudos [?]: 628 [2] , given: 3

GMAT Tests User
Re: range [#permalink] New post 13 Apr 2011, 08:29
2
This post received
KUDOS
AnkitK wrote:
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?

A.693
B.700
C.707
D.777
E.847


The solutions above are great - just another way to look at things (and the answer certainly is A here):

Multiples are equally spaced. If you take any set of 100 consecutive multiples of 7, the range will always be the same; the smallest number in the list is irrelevant. So you can ignore the 'greater than 70' condition in the question, and just look at the first 100 positive multiples of 7: {7, 14, 21, 28, ..., 700}, which has a range of 693.

_________________

Nov 2011: After years of development, I am now making my advanced Quant books and high-level problem sets available for sale. Contact me at ianstewartgmat at gmail.com for details.

Private GMAT Tutor based in Toronto

1 KUDOS received
Manager
Manager
User avatar
Status: ==GMAT Ninja==
Joined: 08 Jan 2011
Posts: 247
Schools: ISB, IIMA ,SP Jain , XLRI
WE 1: Aditya Birla Group (sales)
WE 2: Saint Gobain Group (sales)
Followers: 4

Kudos [?]: 43 [1] , given: 46

GMAT Tests User
Re: range [#permalink] New post 14 Apr 2011, 11:50
1
This post received
KUDOS
fluke wrote:
AnkitK wrote:
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?

A.693
B.700
C.707
D.777
E.847


a_1=77
a_{100}=77+(99)*7=693+77

Range = 693+77-77=693

Ans: "A"


why is 99 is multiplied by 7?[/quote]

In an arithmetic progression
A_n=A_1+(n-1)*d

{77,84,91,98,.....,}
A_1=First \hspace{2} term=77
d=Common \hspace{2} Difference=7

A_{100}=A_1+(n-1)*d
A_{100}=77+(100-1)*7
A_{100}=77+99*7
A_{100}-A_1=77+99*7-77=99*7[/quote]

Hey fluke
i did it bit simpler

without any condition highest no among the first 100 multiple would be 100 x 7 =700
and highest among the first 10 multiple would be 10 x 7 = 70
so if we want to skip the first 10 multiple then we just need to add 70 to the previous 700 right?
it came 770 and now first multiple greater than 70 is simply 77
so answer is 770-77 = 693

please guide me if i am right

_________________

WarLocK
_____________________________________________________________________________
The War is oNNNNNNNNNNNNN for 720+
see my Test exp here http://gmatclub.com/forum/my-test-experience-111610.html
do not hesitate me giving kudos if you like my post. :)

1 KUDOS received
Intern
Intern
avatar
Joined: 17 Oct 2011
Posts: 16
Followers: 1

Kudos [?]: 3 [1] , given: 2

GMAT Tests User
Re: Range of multiples of 7 [#permalink] New post 22 Nov 2011, 18:41
1
This post received
KUDOS
I got the answer as 693. Here is how I approached it.
first multiple of 7 after 70 is = 70 + 7.
second multiple of 7 after 70 = 70 + 7 + 7.
Here is a pattern 70 + n x 7.

If n =100 => we get 770.

range 770 - 77 = 693.

_________________

We will either find a way, or make one.

Please consider giving kudos if you find my post hepful :-)

Intern
Intern
User avatar
Joined: 20 Aug 2010
Posts: 41
Followers: 1

Kudos [?]: 11 [0], given: 0

Re: Range of multiples of 7 [#permalink] New post 23 Nov 2011, 03:52
last term = d*(n-1)
d = 7, n=100
7(99) = 693

A.
Expert Post
2 KUDOS received
Veritas Prep GMAT Instructor
User avatar
Joined: 16 Oct 2010
Posts: 4566
Location: Pune, India
Followers: 1029

Kudos [?]: 4455 [2] , given: 162

Re: Range of multiples of 7 [#permalink] New post 23 Nov 2011, 04:50
2
This post received
KUDOS
Expert's post
enigma123 wrote:
What is the range of a set consisting of the first 100 multiples of 7 that are greater than 70?
(A) 693 (B) 700 (C) 707 (D) 777 (E) 847

I got the answer as 693 i.e. A. But, I solved it by counting i.e from 77 to 770. Is there any shortcut guys?


Another logical approach:
In this question, we talk about only positive multiples.

First multiple of 7 = 7*1
Second multiple of 7 = 7*2
...
100th multiple of 7 = 7*100
But we don't want the first ten multiples (upto 7*10).
First acceptable multiple = 7*11 = 77
So to get a total of 100 multiples, we need to go 10 steps extra after 100 and take upto 110th multiple.
110th multiple of 7 = 7*110 = 770
Range = 770 - 77 = 693

_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Save $100 on Veritas Prep GMAT Courses And Admissions Consulting
Enroll now. Pay later. Take advantage of Veritas Prep's flexible payment plan options.

Veritas Prep Reviews

Manager
Manager
User avatar
Joined: 28 Jul 2011
Posts: 213
Followers: 0

Kudos [?]: 26 [0], given: 13

Re: Range of multiples of 7 [#permalink] New post 27 Jun 2012, 12:38
A

Solved it following way

number of elements in the set formula = (last multiple of x) - (first multiple of x) / x + 1

first multiple of x >70 = 77
(last multiple of x) = x
number of elements in the set = 100

note (x-77) is also a range of set

therefore
(x-77) / 7 + 1 = 100
(x-77) / 7 = 99
(x-77) = 99 * 7 = 693
1 KUDOS received
Current Student
User avatar
Joined: 08 Jan 2009
Posts: 334
GMAT 1: 770 Q50 V46
Followers: 21

Kudos [?]: 76 [1] , given: 7

GMAT Tests User
Re: What is the range of a set consisting of the first 100 [#permalink] New post 28 Jun 2012, 00:46
1
This post received
KUDOS
a_1 = 77
a_2 = 84
a_3 = 91
a_n = 77 + (n-1)*7

Range:a_{100} - a_{1} = (n-1)*7

99*7 = 693

_________________

My Debrief

Senior Manager
Senior Manager
avatar
Joined: 06 Aug 2011
Posts: 408
Followers: 2

Kudos [?]: 47 [0], given: 82

CAT Tests
Re: What is the range of a set consisting of the first 100 [#permalink] New post 28 Jun 2012, 08:52
I select B first :(.. then i cheked the OA..:(.. bt my mistake was i was subtracting 70 from 770.. but question is saying above 70..


but i did this way..

till 70 its 10 multiple of 7 but we dont need those multiples, so we will calculate 110 multiple of 7..

7*110=770..

question is saying multiple of 7 above 70.. so first multiple of 7 after 70 is 77 .. so so so.. to get the range we subtract max-min value..

770-77=693...Answer is A..

_________________

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

Intern
Intern
avatar
Joined: 30 Apr 2010
Posts: 21
Followers: 0

Kudos [?]: 7 [0], given: 2

Re: What is the range of a set consisting of the first 100 [#permalink] New post 17 Jul 2012, 15:19
First multiple greater than 70: 7x10 is 7x11. 100 first multiples so our last multiple is 7x110.

Range = Maximum - Minimum of a set S.

(7x110) - (7x11) = 7x99 = 693
SVP
SVP
User avatar
Joined: 09 Sep 2013
Posts: 1710
Followers: 162

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

Premium Member
Re: range [#permalink] New post 14 Jan 2014, 16:49
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Re: range   [#permalink] 14 Jan 2014, 16:49
    Similar topics Author Replies Last post
Similar
Topics:
Experts publish their posts in the topic What is the range of set S? nishant.1987 1 21 Jun 2014, 00:35
Experts publish their posts in the topic Set S contains 100 consecutive integers. If the range of the sunita123 2 06 Apr 2014, 14:40
What is the range of a set consisting of the first 100 enigma123 0 12 Sep 2013, 22:51
9 Experts publish their posts in the topic What could be the range of a set consisting of odd multiples dimitri92 13 27 May 2010, 00:48
What is the price range for 100 books? (1) The most arjtryarjtry 3 05 Sep 2008, 18:02
Display posts from previous: Sort by

What is the range of a set consisting of the first 100 multi

  Question banks Downloads My Bookmarks Reviews Important topics  

Go to page    1   2    Next  [ 21 posts ] 



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®.