It is currently 11 Dec 2017, 06:35

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4

Author Message
TAGS:

### Hide Tags

Director
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 532

Kudos [?]: 4306 [0], given: 217

Location: United Kingdom
GMAT 1: 730 Q49 V45
GPA: 2.9
WE: Information Technology (Consulting)
Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

12 Jan 2012, 03:28
4
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

61% (01:57) correct 39% (02:03) wrong based on 202 sessions

### HideShow timer Statistics

Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 and S7 = 316, what is the first value of n for which Qn is an integer?

(A) 1
(B) 2
(C) 3
(D) 4
(E) 5
[Reveal] Spoiler: OA

_________________

Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610
GMAT ==> 730

Kudos [?]: 4306 [0], given: 217

Senior Manager
Joined: 30 Aug 2009
Posts: 281

Kudos [?]: 194 [1], given: 5

Location: India
Concentration: General Management
Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

12 Jan 2012, 04:00
1
KUDOS
enigma123 wrote:
Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 and S7 = 316, what is the first value of n for which Qn is an integer?
(A) 1
(B) 2
(C) 3
(D) 4
(E) 5

Any idea how to solve these guys? I have given up after scratching my head for a while.

Assuming I have understood the symbols used correctly answer is C- 3

S7 = 2S6 +4 = 316

S6 = 312/2 = 156 = 2S5 + 4

S5 = 152/2 = 76 = Q4

Q4 = 4Q3 + 8 = 76

Q3 = 68/4 = 17

Q3 = 4Q2 + 8 = 17

Q2 = 9/4 = 2.25

Q2 = 4Q1 + 8

Q1 will not be integer

Kudos [?]: 194 [1], given: 5

Director
Status: Tutor - BrushMyQuant
Joined: 05 Apr 2011
Posts: 613

Kudos [?]: 810 [1], given: 59

Location: India
Concentration: Finance, Marketing
Schools: XLRI (A)
GMAT 1: 700 Q51 V31
GPA: 3
WE: Information Technology (Computer Software)
Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

05 Nov 2014, 21:11
1
KUDOS

Kudos [?]: 810 [1], given: 59

Director
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 532

Kudos [?]: 4306 [0], given: 217

Location: United Kingdom
GMAT 1: 730 Q49 V45
GPA: 2.9
WE: Information Technology (Consulting)
Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

12 Jan 2012, 22:11
Many thanks kp1811. Really appreciate your help.
_________________

Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610
GMAT ==> 730

Kudos [?]: 4306 [0], given: 217

Non-Human User
Joined: 09 Sep 2013
Posts: 14948

Kudos [?]: 287 [0], given: 0

Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

26 Oct 2014, 04:46
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.
_________________

Kudos [?]: 287 [0], given: 0

Math Expert
Joined: 02 Sep 2009
Posts: 42544

Kudos [?]: 135217 [0], given: 12673

Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

06 Nov 2014, 06:43
nktdotgupta wrote:
Please change the OA to C

_______________
Done. Thank you.
_________________

Kudos [?]: 135217 [0], given: 12673

Non-Human User
Joined: 09 Sep 2013
Posts: 14948

Kudos [?]: 287 [0], given: 0

Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

17 Nov 2015, 10:39
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.
_________________

Kudos [?]: 287 [0], given: 0

Intern
Joined: 11 Jan 2014
Posts: 31

Kudos [?]: 13 [0], given: 58

Location: Viet Nam
Concentration: Accounting, Finance
GPA: 3.17
WE: Analyst (Accounting)
Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

28 Jan 2016, 02:56
Is there any shortcut for this question? It took me 4 mins to solve this question.
_________________

Never forget what you are fighting for...
and when your mind and your body tell you to quit. Your heart will tell you to fight.

Kudos [?]: 13 [0], given: 58

Manager
Status: Build your own dreams,Otherwise some one else will hire you to build there's.
Joined: 30 Apr 2015
Posts: 95

Kudos [?]: 27 [0], given: 30

Location: India
Concentration: Finance
Schools: BYU-Marriott'18
GMAT 1: 590 Q45 V26
GMAT 2: 660 Q47 V34
GPA: 3.68
Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

16 Feb 2016, 23:14
I wonder,why is it 700 level que?
It is quite simple
it is given
$$2S_4=4Q_3+4$$
$$S_4=2[Q_3+1]$$....i

we have been given that S_7=316
from this we can calculate S_6 and then ultimately S_4
$$S_4=36$$
putting this in equ i
$$Q_3=17$$ ...ans
_________________

-Dori Roberts

Kudos [?]: 27 [0], given: 30

Intern
Joined: 11 Nov 2015
Posts: 20

Kudos [?]: 13 [0], given: 57

Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4 [#permalink]

### Show Tags

18 Feb 2016, 07:18
mahakmalik wrote:
I wonder,why is it 700 level que?
It is quite simple
it is given
$$2S_4=4Q_3+4$$
$$S_4=2[Q_3+1]$$....i

we have been given that S_7=316
from this we can calculate S_6 and then ultimately S_4
$$S_4=36$$
putting this in equ i
$$Q_3=17$$ ...ans

I think it's because it is long to solve and you have a big chance to make mistakes while calculating given that we deal with big numbers

Kudos [?]: 13 [0], given: 57

Re: Sn = 2Sn-1 + 4 and Qn = 4Qn-1 + 8 for all n > 1. If S5 = Q4   [#permalink] 18 Feb 2016, 07:18
Display posts from previous: Sort by