It is currently 24 Nov 2017, 01:12

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

3 KUDOS received
VP
VP
User avatar
Status: Far, far away!
Joined: 02 Sep 2012
Posts: 1120

Kudos [?]: 2382 [3], given: 219

Location: Italy
Concentration: Finance, Entrepreneurship
GPA: 3.8
GMAT ToolKit User
Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t [#permalink]

Show Tags

New post 12 Apr 2013, 01:10
3
This post received
KUDOS
3
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

67% (01:20) correct 33% (01:47) wrong based on 164 sessions

HideShow timer Statistics

Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such that A has an even number of terms. If the sum of terms at odd positions is p and sum of terms at even positions is q, what is the ratio of p to q (take the common ratio as r)?

(A) r
(B) r2
(C) 1/r2
(D) 1/r
(E) None of these
[Reveal] Spoiler: OA

_________________

It is beyond a doubt that all our knowledge that begins with experience.

Kant , Critique of Pure Reason

Tips and tricks: Inequalities , Mixture | Review: MGMAT workshop
Strategy: SmartGMAT v1.0 | Questions: Verbal challenge SC I-II- CR New SC set out !! , My Quant

Rules for Posting in the Verbal Forum - Rules for Posting in the Quant Forum[/size][/color][/b]

Kudos [?]: 2382 [3], given: 219

Intern
Intern
avatar
Joined: 15 Oct 2012
Posts: 25

Kudos [?]: 16 [0], given: 1

GMAT ToolKit User
Re: Latest Grail question bank PS 700 level [#permalink]

Show Tags

New post 12 Apr 2013, 01:37
i guess GP over here means Geometric Progression....

Kudos [?]: 16 [0], given: 1

Expert Post
4 KUDOS received
MBA Section Director
User avatar
P
Status: Back to work...
Affiliations: GMAT Club
Joined: 22 Feb 2012
Posts: 4784

Kudos [?]: 3801 [4], given: 2448

Location: India
City: Pune
GMAT 1: 680 Q49 V34
GPA: 3.4
WE: Business Development (Manufacturing)
GMAT ToolKit User Premium Member
Re: Latest Grail question bank PS 700 level [#permalink]

Show Tags

New post 12 Apr 2013, 01:49
4
This post received
KUDOS
Expert's post
I think it should be 1/r

Let A be the GP with first term as a , common ratio as r, and number of terms as 6

GP = a, ar, ar^2, ar^3, ar^4, ar^5

Sum of GP = \(\frac{a (r^n - 1)}{r-1}\) where a=first term, n=number of terms, r=common ratio

Odd GP = a, ar^2, ar^4 Sum odd GP = \(\frac{a (r^6 - 1)}{r^2-1}\)

Even GP = ar, ar^3, ar^5 Sum even GP = \(\frac{ar (r^6 - 1)}{r^2-1}\)

Desired Ratio = \(\frac{a}{ar}\) = \(\frac{1}{r}\)

PS :- G.P. means Geometric Progression
_________________

Every Wednesday: Meet MBA Experts in Chat Room and Ask Your Most-Pressing MBA Admission Questions to them in a Live Chat.

Must Read Forum Topics Before You Kick Off Your MBA Application

New GMAT Club Decision Tracker - Real Time Decision Updates

Kudos [?]: 3801 [4], given: 2448

1 KUDOS received
Current Student
User avatar
Joined: 04 Mar 2013
Posts: 68

Kudos [?]: 58 [1], given: 27

Location: India
Concentration: Strategy, Operations
Schools: Booth '17 (M)
GMAT 1: 770 Q50 V44
GPA: 3.66
WE: Operations (Manufacturing)
Reviews Badge
Re: Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such [#permalink]

Show Tags

New post 12 Apr 2013, 04:56
1
This post received
KUDOS
You dont need to know the formula for the Sum of GP to solve this

Just write the odd and even digits of the given statement together

P would become a +ar^2 + ar^4

Q would become ar + ar^3 + ar^5

=> P/Q = a(1 + r^2 + r^4) / ar (1 + r^2 + r^4)
=> P/Q = a(1 + r^2 + r^4) / ar(1 + r^2 + r^4)
=> P/Q = a/ar
=> P/Q = 1/r
_________________

When you feel like giving up, remember why you held on for so long in the first place.

Kudos [?]: 58 [1], given: 27

Manager
Manager
avatar
Status: Do till 740 :)
Joined: 13 Jun 2011
Posts: 108

Kudos [?]: 13 [0], given: 19

Concentration: Strategy, General Management
GMAT 1: 460 Q35 V20
GPA: 3.6
WE: Consulting (Computer Software)
GMAT ToolKit User
Re: Latest Grail question bank PS 700 level [#permalink]

Show Tags

New post 27 Oct 2013, 17:01
Narenn wrote:
I think it should be 1/r

Let A be the GP with first term as a , common ratio as r, and number of terms as 6

GP = a, ar, ar^2, ar^3, ar^4, ar^5

Sum of GP = \(\frac{a (r^n - 1)}{r-1}\) where a=first term, n=number of terms, r=common ratio

Odd GP = a, ar^2, ar^4 Sum odd GP = \(\frac{a (r^6 - 1)}{r^2-1}\)

Even GP = ar, ar^3, ar^5 Sum even GP = \(\frac{ar (r^6 - 1)}{r^2-1}\)

Desired Ratio = \(\frac{a}{ar}\) = \(\frac{1}{r}\)

PS :- G.P. means Geometric Progression


Hi, how can the number of terms be 6. It must be 3 right? Since for the even and odd terms it is just 3. Is that correct?

Please clarify!
Thanks

Kudos [?]: 13 [0], given: 19

Manager
Manager
avatar
Joined: 29 Sep 2013
Posts: 51

Kudos [?]: 41 [0], given: 48

Re: Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t [#permalink]

Show Tags

New post 03 Nov 2013, 18:15
Zarrolou wrote:
Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such that A has an even number of terms. If the sum of terms at odd positions is p and sum of terms at even positions is q, what is the ratio of p to q (take the common ratio as r)?

(A) r
(B) r2
(C) 1/r2
(D) 1/r
(E) None of these


If A = (\(a, ar, ar^2, ar^4,\)…), then shouldn't the next terms be \(ar^8\) and \(ar^16\). or am I missing something.

Kudos [?]: 41 [0], given: 48

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 15503

Kudos [?]: 283 [0], given: 0

Premium Member
Re: Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t [#permalink]

Show Tags

New post 04 Sep 2015, 11:34
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

Kudos [?]: 283 [0], given: 0

Manager
Manager
User avatar
Joined: 23 Sep 2015
Posts: 93

Kudos [?]: 19 [0], given: 213

Concentration: General Management, Finance
GMAT 1: 680 Q46 V38
GMAT 2: 690 Q47 V38
GPA: 3.5
Re: Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t [#permalink]

Show Tags

New post 06 Nov 2015, 21:34
Narenn wrote:
I think it should be 1/r

Let A be the GP with first term as a , common ratio as r, and number of terms as 6

GP = a, ar, ar^2, ar^3, ar^4, ar^5

Sum of GP = \(\frac{a (r^n - 1)}{r-1}\) where a=first term, n=number of terms, r=common ratio

Odd GP = a, ar^2, ar^4 Sum odd GP = \(\frac{a (r^6 - 1)}{r^2-1}\)

Even GP = ar, ar^3, ar^5 Sum even GP = \(\frac{ar (r^6 - 1)}{r^2-1}\)

Desired Ratio = \(\frac{a}{ar}\) = \(\frac{1}{r}\)

PS :- G.P. means Geometric Progression



how did the denominator change from r-1 to r^2-1 ?

Kudos [?]: 19 [0], given: 213

Intern
Intern
avatar
Joined: 12 Jun 2011
Posts: 2

Kudos [?]: 5 [0], given: 27

GMAT 1: 690 Q49 V35
Re: Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t [#permalink]

Show Tags

New post 14 Dec 2015, 21:17
Please correct the question.
A = {a, ar, ar2, ar4,…..} <--- This is not a GP.
A = {a, ar, ar2, ar3,…..} <--- This is.

Kudos [?]: 5 [0], given: 27

Re: Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t   [#permalink] 14 Dec 2015, 21:17
Display posts from previous: Sort by

Let A be a G.P. defined by A = {a, ar, ar2, ar4,…..}, such t

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

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®.