GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 22 Sep 2018, 11:59

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

The average score of x number of exams is y

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
SVP
SVP
User avatar
Joined: 24 Sep 2005
Posts: 1816
The average score of x number of exams is y  [#permalink]

Show Tags

New post 13 Oct 2005, 23:05
4
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

73% (01:15) correct 27% (00:39) wrong based on 74 sessions

HideShow timer Statistics

Question
The average score of x number of exams is y. When an additional exam of score z is added in, does the average score of the exams increase by 50%?
(1) 3x = y

(2) 2z - 3y = xy

(A) Statement (1) ALONE is sufficient to answer the question, but statement (2) alone is not.
(B) Statement (2) ALONE is sufficient to answer the question, but statement (1) alone is not.
(C) Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient.
(D) EACH statement ALONE is sufficient to answer the question.
(E) Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question.

Answer

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.


If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.
GMAT Club Legend
GMAT Club Legend
User avatar
B
Joined: 29 Jan 2005
Posts: 5062
  [#permalink]

Show Tags

New post 13 Oct 2005, 23:12
B.

I just picked numbers for X, Y, and Z. But the problem is probably much more difficult than this...

OA?
Manager
Manager
User avatar
Joined: 03 Aug 2005
Posts: 132
  [#permalink]

Show Tags

New post 14 Oct 2005, 02:57
1
To get a 50% increase:

(xy+z)/(x+1)=1'5y and this is exactly what (2) says
Manager
Manager
avatar
Joined: 04 May 2005
Posts: 133
Location: Chicago
  [#permalink]

Show Tags

New post 14 Oct 2005, 10:38
I did GMATT's way. Anyone got a better way? Anyone? Anyone?

jdto, could you elaborate?
_________________

Christopher Wilson

Senior Manager
Senior Manager
avatar
Joined: 26 Jul 2005
Posts: 306
Location: Los Angeles
  [#permalink]

Show Tags

New post 14 Oct 2005, 10:53
Can someone explain the approach in a little more detail?

Thanks!
Director
Director
avatar
Joined: 21 Aug 2005
Posts: 763
  [#permalink]

Show Tags

New post 14 Oct 2005, 11:13
2
2
B

Sum of all numbers = xy
New number = z
New Average = xy+z/(x+1)
We need to find if xy+z/(x+1) = 3y/2 --- (1)

A) We don't have z. So Insufficient
B) Simplify (1),
we get 2xy+2z=3xy+3y => 3z-3y=xy which the same as (B)
Hence Suff.
VP
VP
avatar
Joined: 22 Aug 2005
Posts: 1090
Location: CA
  [#permalink]

Show Tags

New post 14 Oct 2005, 11:21
In order for 50% increase in ang scope, z has to be equal to difference between old score sum (x * y) and new score sum ((x+1) * 1.5 y). OR

z = (x+1) * 1.5 y - xy or
z = 0.5 y (x +3) or
z = 1/2 y (x + 3)

(1) tells relationship between x and y only insufficient

(2) simplifying we get:
z = 1/2y(x+3)
exactly what we want.
ans: yes, sufficient
Senior Manager
Senior Manager
avatar
Joined: 26 Jul 2005
Posts: 306
Location: Los Angeles
  [#permalink]

Show Tags

New post 14 Oct 2005, 11:24
Cool - thanks for the detailed steps!
SVP
SVP
User avatar
Joined: 24 Sep 2005
Posts: 1816
  [#permalink]

Show Tags

New post 14 Oct 2005, 20:12
OA is B. OE is the same to gsr's.
Director
Director
avatar
Joined: 10 Feb 2006
Posts: 647
average  [#permalink]

Show Tags

New post 11 Jun 2008, 06:59
1. The average score of x number of exams is y. When an additional exam of score z is added in, does the average score of the exams increase by 50%?
(1) 3x = y
(2) 2z - 3y = xy

(A) Statement (1) ALONE is sufficient to answer the question, but statement (2) alone is not.
(B) Statement (2) ALONE is sufficient to answer the question, but statement (1) alone is not.
(C) Statements (1) and (2) TAKEN TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient.
(D) EACH statement ALONE is sufficient to answer the question.
(E) Statements (1) and (2) TAKEN TOGETHER are NOT sufficient to answer the question.
_________________

GMAT the final frontie!!!.

Director
Director
avatar
Joined: 01 Jan 2008
Posts: 600
Re: average  [#permalink]

Show Tags

New post 11 Jun 2008, 07:37
average after adding z is (xy+z)/(x+1) and compare to 1.5*y

1) insufficient (z can be anything)
2) sufficient z = (xy+3y)/2 => (xy+z)/(x+1) = 3*(xy+y)/2/(x+1)=1.5y -> sufficient

B is the answer
Director
Director
avatar
Joined: 10 Feb 2006
Posts: 647
Re: average  [#permalink]

Show Tags

New post 11 Jun 2008, 07:55
great stuff, how long did it take you to solve this ?
_________________

GMAT the final frontie!!!.

Director
Director
avatar
Joined: 01 Jan 2008
Posts: 600
Re: average  [#permalink]

Show Tags

New post 11 Jun 2008, 08:31
alimad wrote:
great stuff, how long did it take you to solve this ?


it was fairly straight-forward for me primarily because of lots of practice long-long time ago.
Manager
Manager
avatar
Joined: 09 Jun 2011
Posts: 95
ADVANCED DATA SUFFICIENCY  [#permalink]

Show Tags

New post 01 Sep 2011, 05:42
The average of a set of x exam scores is y. When an additional exam of score z is added to the set, does the average score of the exams increase by 50%?

(1) 3x = y
(2) 2z – 3y = xy

Hey Guys! I need Help, what would be the best answer, please explain.
Intern
Intern
avatar
Joined: 16 Apr 2010
Posts: 28
Location: United States (AL)
Concentration: Technology, Entrepreneurship
GMAT 1: 680 Q44 V37
GPA: 3.91
WE: Information Technology (Energy and Utilities)
Re: ADVANCED DATA SUFFICIENCY  [#permalink]

Show Tags

New post 01 Sep 2011, 11:05
The answer is B.

The question asks if the new average, with z, greater than the old average(y) by 50%?

We know that the sum of the numbers in the set is xy (no. of terms x average of terms).
so when a new term,z, is added to the set, the new average becomes (xy+z)/(x+1).
Plugging this in to the question, we get : is (xy+z)/(x+1) = 1.5y ?
Simplifying both sides, the answer is 2z – 3y = xy viz B.


bholakc wrote:
The average of a set of x exam scores is y. When an additional exam of score z is added to the set, does the average score of the exams increase by 50%?

(1) 3x = y
(2) 2z – 3y = xy

Hey Guys! I need Help, what would be the best answer, please explain.
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 8154
Premium Member
Re: The average score of x number of exams is y  [#permalink]

Show Tags

New post 14 Feb 2018, 07:03
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.

--== Message from the GMAT Club Team ==--

THERE IS LIKELY A BETTER DISCUSSION OF THIS EXACT QUESTION.
This discussion does not meet community quality standards. It has been retired.


If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________

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

GMAT Club Bot
Re: The average score of x number of exams is y &nbs [#permalink] 14 Feb 2018, 07:03
Display posts from previous: Sort by

The average score of x number of exams is y

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

Events & Promotions

PREV
NEXT


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.