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

It is currently 24 Jul 2014, 13:37

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

Some good questions..Require solution

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 06 Sep 2009
Posts: 8
Followers: 0

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

Some good questions..Require solution [#permalink] New post 08 Nov 2009, 11:18
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

50% (03:20) correct 50% (01:18) wrong based on 3 sessions
1.
A certain company assigns employees to offices in such a way that some of the offices
can be empty and more than one employee can be assigned to an office. In how many
ways can the company assign 3 employees to 2 different offices?

A. 5
B. 6
C. 7
D. 8
E. 9

2.The infinite sequence a1, a2,…, an,… is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an =
an-4 for n > 4. What is the sum of the first 97 terms of the sequence?

A. 72
B. 74
C. 75
D. 78
E. 80
VP
VP
avatar
Joined: 05 Mar 2008
Posts: 1477
Followers: 11

Kudos [?]: 193 [0], given: 31

GMAT Tests User
Re: Some good questions..Require solution [#permalink] New post 08 Nov 2009, 11:51
alok2171 wrote:
1.
A certain company assigns employees to offices in such a way that some of the offices
can be empty and more than one employee can be assigned to an office. In how many
ways can the company assign 3 employees to 2 different offices?

A. 5
B. 6
C. 7
D. 8
E. 9


8 ways

Assuming 1 office
# of ways with 3 employees = 1
# of ways with 2 employees = 3
total = 4
two office so answer = 8
VP
VP
avatar
Joined: 05 Mar 2008
Posts: 1477
Followers: 11

Kudos [?]: 193 [0], given: 31

GMAT Tests User
Re: Some good questions..Require solution [#permalink] New post 08 Nov 2009, 12:02
alok2171 wrote:

2.The infinite sequence a1, a2,…, an,… is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an =
an-4 for n > 4. What is the sum of the first 97 terms of the sequence?

A. 72
B. 74
C. 75
D. 78
E. 80


a1 = 2
a2 = -3
a3 = 5
a4 = -1
a5=a5-4= a1
a6=a2 and so on and so forth

In other words, the 4 numbers given are the only ones in the sequence
We need 97 terms total. Therefore, each term will be seen at least 24 times and 4 times 24 = 96 and the first number will be seen 5 times because we need 97 total:

2 x 25 = 50
-3 x 24 = -72
5 x 24 = 120
-1 x 24 = -24

multiply and add and you get 74
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 18728
Followers: 3239

Kudos [?]: 22345 [0], given: 2615

Re: Some good questions..Require solution [#permalink] New post 08 Nov 2009, 12:04
Expert's post
alok2171 wrote:
1.
A certain company assigns employees to offices in such a way that some of the offices
can be empty and more than one employee can be assigned to an office. In how many
ways can the company assign 3 employees to 2 different offices?

A. 5
B. 6
C. 7
D. 8
E. 9


Each of 3 employees has 2 offices to be assigned so the total # of ways is 2^3=8

Answer: D

alok2171 wrote:
2.The infinite sequence a1, a2,…, an,… is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an =
an-4 for n > 4. What is the sum of the first 97 terms of the sequence?

A. 72
B. 74
C. 75
D. 78
E. 80


I guess that an=an-4? If so than:

a1=a5, a2=6, a3=a7 etc. So we'll have the sequence 2,-3,5,-1, 2,-3,5,-1, 2,-3,5,-1, ... 97 terms.

The sum of group of four terms 2,-3,5,-1 is 3. We'll have 97/4=24 full groups of four, plus 97th term 2.

The sum would be 24*3+2=74

Answer: B.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
avatar
Joined: 26 Jan 2010
Posts: 8
Followers: 0

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

Sequence [#permalink] New post 02 May 2010, 08:18
The infinite sequence a1, a2,..., an,... is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an =
an-4 for n > 4. What is the sum of the first 97 terms of the sequence?
A. 72
B. 74
C. 75
D. 78
E. 80
Senior Manager
Senior Manager
avatar
Joined: 25 Jun 2009
Posts: 313
Followers: 2

Kudos [?]: 70 [0], given: 6

GMAT Tests User
Re: Sequence [#permalink] New post 02 May 2010, 10:20
chaitu1315 wrote:
The infinite sequence a1, a2,..., an,... is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an =
an-4 for n > 4. What is the sum of the first 97 terms of the sequence?
A. 72
B. 74
C. 75
D. 78
E. 80



Is An = A (n-4) ?

If yes then the answer should be B

A5= A (5-4) = A 1 = 2
similarly A 6 = -3 and this sequence will repeat after every 4 terms

A1 + A 2+ A3 + A4 = 2- 3+ 5-1 = 3

now Sum of first 96 terms = 3 *24
Sum of 97 terms = 72 + 2 = 74

Last edited by cipher on 02 May 2010, 10:54, edited 1 time in total.
Intern
Intern
avatar
Joined: 26 Jan 2010
Posts: 8
Followers: 0

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

Re: Sequence [#permalink] New post 02 May 2010, 10:50
nitishmahajan wrote:
chaitu1315 wrote:
The infinite sequence a1, a2,..., an,... is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an =
an-4 for n > 4. What is the sum of the first 97 terms of the sequence?
A. 72
B. 74
C. 75
D. 78
E. 80



Is An = A (n-4) ?

If yes then the answer should be B

A5= A (5-4) = A 1 = 2
similarly A 6 = -3 and this sequence will repeat after every 4 terms

A1 + A 2+ A3 + A4 = 2- 3+ 5-1 = 2

now Sum of first 96 terms = 2 *24
Sum of 97 terms = 72 + 2 = 74


I understood until the point that as after 4 we have repeat of the sequence, you can say 96/4= 24...as sum of 4 terms is 2, so 2*24= 48...from where did 72 come from...can you explain it further....
Senior Manager
Senior Manager
avatar
Joined: 25 Jun 2009
Posts: 313
Followers: 2

Kudos [?]: 70 [0], given: 6

GMAT Tests User
Re: Sequence [#permalink] New post 02 May 2010, 10:54
chaitu1315 wrote:
nitishmahajan wrote:
chaitu1315 wrote:
The infinite sequence a1, a2,..., an,... is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an =
an-4 for n > 4. What is the sum of the first 97 terms of the sequence?
A. 72
B. 74
C. 75
D. 78
E. 80



Is An = A (n-4) ?

If yes then the answer should be B

A5= A (5-4) = A 1 = 2
similarly A 6 = -3 and this sequence will repeat after every 4 terms

A1 + A 2+ A3 + A4 = 2- 3+ 5-1 = 2

now Sum of first 96 terms = 2 *24
Sum of 97 terms = 72 + 2 = 74


I understood until the point that as after 4 we have repeat of the sequence, you can say 96/4= 24...as sum of 4 terms is 2, so 2*24= 48...from where did 72 come from...can you explain it further....


my bad again the was 3 and not 3 edited the post ..!
Re: Sequence   [#permalink] 02 May 2010, 10:54
    Similar topics Author Replies Last post
Similar
Topics:
14 Experts publish their posts in the topic Another set with solutions. good luck to you all for the Marcab 3 10 Dec 2012, 19:16
3 Good questions on number theory with solutions pkmme 2 27 Jun 2011, 05:49
Experts publish their posts in the topic Some good questions..Require solution alok2171 7 08 Nov 2009, 11:18
Some good prep material Sergey_is_cool 5 24 May 2007, 06:25
Need some good wishes :-) aspire2005 6 12 Nov 2004, 06:48
Display posts from previous: Sort by

Some good questions..Require solution

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.