It is currently 21 Oct 2017, 20:16

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

If the average(arithmetic mean) of four numbers is 10 ,how many of the

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

Hide Tags

Manager
Manager
avatar
B
Joined: 24 Jun 2014
Posts: 52

Kudos [?]: 23 [0], given: 97

Concentration: Social Entrepreneurship, Nonprofit
GMAT ToolKit User CAT Tests
If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 27 Feb 2015, 21:22
5
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  85% (hard)

Question Stats:

48% (01:18) correct 52% (01:31) wrong based on 129 sessions

HideShow timer Statistics

If the average(arithmetic mean) of four numbers is 10 ,how many of the numbers are greater than 10?

1) Precisely two numbers are equal to 10

2) The largest of the 4 numbers is 10 greater than the smallest of the 4 numbers.
[Reveal] Spoiler: OA

Kudos [?]: 23 [0], given: 97

Expert Post
1 KUDOS received
EMPOWERgmat Instructor
User avatar
P
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 9988

Kudos [?]: 3413 [1], given: 172

Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 27 Feb 2015, 23:53
1
This post received
KUDOS
Expert's post
1
This post was
BOOKMARKED
Hi AverageGuy123,

This question has some very specific 'restrictions' to it, but if you take the proper notes and TEST VALUES, you can answer this question without too much trouble.

We're told that the average of 4 numbers is 10. We're asked how many (of those 4) are greater than 10.

From the first sentence, we can create an equation:

(W + X + Y + Z)/4 = 10
W + X + Y + Z = 40

Fact 1: Precisely 2 of the numbers equal 10

I'm going to "lock in" the W and the X as 10s....

10 + 10 + Y + Z = 40
Y + Z = 20

Since Fact 1 states that PRECISELY 2 of the numbers equal 10, neither Y nor Z can now be 10s. That means we need 2 numbers that add up to 20 and NEITHER can be a 10...

9 and 11
8 and 12
0 and 20
-1 and 21
Etc.
In EVERY possible example, one number is LESS than 10 and ONE number is GREATER than 10. Thus, the answer to the question is ALWAYS ONE number.
Fact 1 is SUFFICIENT

Fact 2: The largest of the numbers is 10 greater than the smallest of the numbers

IF... the numbers are....
5, 10, 10 and 15.... then the answer to the question is ONE.
4, 10, 12 and 14.... then the answer to the question is TWO.
Fact 2 is INSUFFICIENT.

Final Answer:
[Reveal] Spoiler:
A


GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free
  Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Kudos [?]: 3413 [1], given: 172

CEO
CEO
User avatar
G
Joined: 17 Jul 2014
Posts: 2605

Kudos [?]: 396 [0], given: 184

Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge CAT Tests
Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 23 Feb 2016, 19:16
now this one is a very tricky one...precisely 2..so other 2 cannot be 10...A for sure...

Kudos [?]: 396 [0], given: 184

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 16589

Kudos [?]: 273 [0], given: 0

Premium Member
Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 09 Mar 2017, 01:26
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 [?]: 273 [0], given: 0

Intern
Intern
avatar
B
Joined: 04 Nov 2015
Posts: 36

Kudos [?]: 2 [0], given: 2

Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 09 Mar 2017, 15:41
mvictor wrote:
now this one is a very tricky one...precisely 2..so other 2 cannot be 10...A for sure...


I dont agree with this no where it is written that the other two numbers can't be 10 and 10.

Kudos [?]: 2 [0], given: 2

1 KUDOS received
CEO
CEO
User avatar
G
Joined: 17 Jul 2014
Posts: 2605

Kudos [?]: 396 [1], given: 184

Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
GMAT ToolKit User Premium Member Reviews Badge CAT Tests
Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 09 Mar 2017, 15:46
1
This post received
KUDOS
sandeep211986 wrote:
mvictor wrote:
now this one is a very tricky one...precisely 2..so other 2 cannot be 10...A for sure...


I dont agree with this no where it is written that the other two numbers can't be 10 and 10.



it clearly says that only 2 are 10:

1) Precisely two numbers are equal to 10

Kudos [?]: 396 [1], given: 184

Expert Post
Math Revolution GMAT Instructor
User avatar
P
Joined: 16 Aug 2015
Posts: 4142

Kudos [?]: 2902 [0], given: 0

GPA: 3.82
Premium Member CAT Tests
Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 09 Mar 2017, 16:31
AverageGuy123 wrote:
If the average(arithmetic mean) of four numbers is 10 ,how many of the numbers are greater than 10?

1) Precisely two numbers are equal to 10

2) The largest of the 4 numbers is 10 greater than the smallest of the 4 numbers.


Assume that \(a\), \(b\), \(c\) and \(d\) are four numbers, where \(a \leq b \leq c \leq d\).
Then we have 1 equation that \(a + b + c + d = 40\).

Let's translate the conditions to mathematical expressions.

1) \(b = c = 10\), \(a < 10\), \(d > 10\)
2) \(d = a + 10\)

For the first condition, only \(d\) is greater than 10 form the above mathematical expression.
Hence the condition 1) is sufficient.

For the second condition, we have following examples.
Let \(a = 5\) and \(d = 15\).
Then we have two kinds of cases as follows.
5, 10, 10, 15 : They have just 1 number of elements greater than 10, which is just 15.
5, 9, 11, 15 : They have 2 numbers of elements greater than 10, which are 11 and 15.
Hence, we don't have a unique solution about the question how many numbers are greater than 10.
Therefore, the second condition is not sufficient.

Please remind that we should forget everything about the condition 1), when we consider the second condition only.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself
See our Youtube demo

Kudos [?]: 2902 [0], given: 0

Intern
Intern
avatar
Joined: 25 May 2015
Posts: 6

Kudos [?]: [0], given: 4

Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the [#permalink]

Show Tags

New post 25 Sep 2017, 22:44
sandeep211986 wrote:
mvictor wrote:
now this one is a very tricky one...precisely 2..so other 2 cannot be 10...A for sure...


I dont agree with this no where it is written that the other two numbers can't be 10 and 10.



I just made the same mistake. :)

Kudos [?]: [0], given: 4

Re: If the average(arithmetic mean) of four numbers is 10 ,how many of the   [#permalink] 25 Sep 2017, 22:44
Display posts from previous: Sort by

If the average(arithmetic mean) of four numbers is 10 ,how many of the

  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®.