It is currently 23 Oct 2017, 14:14

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

Class A and class B took the same test. The average

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

Hide Tags

Manager
Manager
User avatar
Joined: 20 Nov 2009
Posts: 164

Kudos [?]: 248 [0], given: 64

Class A and class B took the same test. The average [#permalink]

Show Tags

New post 22 Jul 2010, 12:35
3
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

72% (00:56) correct 28% (00:34) wrong based on 74 sessions

HideShow timer Statistics

Class A and class B took the same test. The average (arithmetic mean) score for class A was 79.5. What was the average score for all the students in both classes?

(1) The average score for class B was 80.5.
(2) Class B had 25 fewer students than class A.
[Reveal] Spoiler: OA

_________________

But there’s something in me that just keeps going on. I think it has something to do with tomorrow, that there is always one, and that everything can change when it comes.
http://aimingformba.blogspot.com

Kudos [?]: 248 [0], given: 64

Current Student
User avatar
Status: Three Down.
Joined: 09 Jun 2010
Posts: 1915

Kudos [?]: 2206 [0], given: 210

Concentration: General Management, Nonprofit
GMAT ToolKit User
Re: DS question [#permalink]

Show Tags

New post 22 Jul 2010, 14:24
Statement 1 gives you the average arithmetic mean for class B but then it doesn't mention how many students were there in the classes. So insufficient.

Statement 2 gives you the comparison between the number of students in the two classes but no information about the mean in class B. So insufficient again.

Putting together, we still don't know the absolute numbers of the number of students in the classes. Hence the answer is E.

Kudos [?]: 2206 [0], given: 210

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 16535

Kudos [?]: 274 [0], given: 0

Premium Member
Re: Class A and class B took the same test. The average [#permalink]

Show Tags

New post 22 Aug 2016, 06:58
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 [?]: 274 [0], given: 0

Intern
Intern
User avatar
B
Status: Researching
Affiliations: NA
Joined: 03 Oct 2014
Posts: 30

Kudos [?]: 7 [0], given: 145

Location: United States (CA)
Concentration: Nonprofit, General Management
GMAT 1: 460 Q14 V36
GMAT 2: 540 Q31 V34
GMAT 3: 610 Q36 V38
GMAT 4: 570 Q29 V40
GPA: 3.11
WE: Account Management (Non-Profit and Government)
Re: Class A and class B took the same test. The average [#permalink]

Show Tags

New post 01 Aug 2017, 17:40
Have: The average (arithmetic mean) score for class A was 79.5.

NEED: What was the average score for all the students in both classes?

Inference: A = sum of Class A scores
B = sum of Class B scores
a= total students in class A
b= total students in class B
x= variable required, average score of students from both classes

Need to solve using this --> (A+B)/(a+b) = x
Have: arithmetic mean for Class A: (A)/(a) = 79.5 or (A)= 79.5(a)

Statement (1) The average score for class B was 80.5.

(B)/(b) = 80.5
In the equation from above we get B= (b)(80.5) but we don't know what (b) is, nor do we have a value for (a)
So the equation looks like this

[(79.5)(a) + (b)(80.5)]/(a+b) = x --> no value for a, or b, so no x NO SUFFICIENT (not A or E)

Statement (2) Class B had 25 fewer students than class A.

b = a-25
a = ?

Equation would look like this: [(A+B)]/[a+a-25] = [(A+B)]/[2a-25] = x; we don't have values for A, B, a, so we can't get x
<b>NO SUFFICIENT</b> (not B)

Together:

From Statement 1: [(79.5)(a) + (b)(80.5)]/(a+b) = x
From Statement 2: b = a-25; a = ?; (A+B)/(2a-25)

[(79.5)(a) + (a-25)(80.5)]/(2a-25) = x where we still don't have a variable for a and not sufficient to find x, so not together (answer choice C)
answer choice E
_________________

Aut viam inveniam aut faciam.

Kudos [?]: 7 [0], given: 145

Re: Class A and class B took the same test. The average   [#permalink] 01 Aug 2017, 17:40
Display posts from previous: Sort by

Class A and class B took the same test. The average

  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®.