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

 It is currently 11 Dec 2018, 21:21

### 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 December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
• ### Free GMAT Prep Hour

December 11, 2018

December 11, 2018

09:00 PM EST

10:00 PM EST

Strategies and techniques for approaching featured GMAT topics. December 11 at 9 PM EST.
• ### The winning strategy for 700+ on the GMAT

December 13, 2018

December 13, 2018

08:00 AM PST

09:00 AM PST

What people who reach the high 700's do differently? We're going to share insights, tips and strategies from data we collected on over 50,000 students who used examPAL.

# What is the average (arithmetic mean) of x and y?

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 51101
What is the average (arithmetic mean) of x and y?  [#permalink]

### Show Tags

24 Dec 2013, 02:42
1
6
00:00

Difficulty:

5% (low)

Question Stats:

87% (01:01) correct 13% (01:13) wrong based on 821 sessions

### HideShow timer Statistics

The Official Guide For GMAT® Quantitative Review, 2ND Edition

What is the average (arithmetic mean) of x and y?

(1) The average of x and 2y is 10.
(2) The average of 2x and 7y is 32.

Data Sufficiency
Question: 1
Category: Algebra Statistics
Page: 153
Difficulty: 550

GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 51101
Re: What is the average (arithmetic mean) of x and y?  [#permalink]

### Show Tags

24 Dec 2013, 02:43
3
2
SOLUTION

What is the average (arithmetic mean) of x and y?

The average (arithmetic mean) of x and y is $$\frac{x+y}{2}$$. Thus we need to find the value of x+y.

(1) The average of x and 2y is 10 --> $$\frac{x+2y}{2}=10$$. Not sufficient.

(2) The average of 2x and 7y is 32 --> $$\frac{2x+7y}{2}=32$$. Not sufficient.

(1)+(2) We have two distinct linear equations with two unknowns, thus we can solve for both and get the value of x+y. Sufficient.

_________________
##### General Discussion
Director
Joined: 27 May 2012
Posts: 631
Re: What is the average (arithmetic mean) of x and y?  [#permalink]

### Show Tags

24 Dec 2013, 15:52
1
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

What is the average (arithmetic mean) of x and y?

(1) The average of x and 2y is 10.
(2) The average of 2x and 7yis 32.

Data Sufficiency
Question: 1
Category: Algebra Statistics
Page: 153
Difficulty: 550

GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!

statement 1 : x+2y= 10

x =8, y = 1, avg = 4.5
x= 6, y = 2, avg = 4

since 2 answers or more hence insufficient.

Statement 2 : 2x+7y=32

x=9 , y =2, avg = 5.5
x=2 , y =4, avg = 3

Since 2 answers or more hence insufficient

1+2

2 equations and 2 unknowns we can solve
on solving we get y = 4 and x = 2 hence avg = 3

Sufficient.

( Difficulty level - 500 )
_________________

- Stne

Manager
Status: GMATting
Joined: 21 Mar 2011
Posts: 105
Concentration: Strategy, Technology
GMAT 1: 590 Q45 V27
Re: What is the average (arithmetic mean) of x and y?  [#permalink]

### Show Tags

25 Dec 2013, 09:55
1
The question asks for average of x and y: (x+y)/2. So, it is sufficient if we know the values of x and y individually or (x+y) as a whole.

With either statements alone, it is not possible to arrive at (x+y) value.
When both statements are together, we can find out the (x+y) value since we have 2 equations and 2 unknowns.

Math Expert
Joined: 02 Sep 2009
Posts: 51101
Re: What is the average (arithmetic mean) of x and y?  [#permalink]

### Show Tags

30 Dec 2013, 03:34
What is the average (arithmetic mean) of x and y?

The average (arithmetic mean) of x and y is $$\frac{x+y}{2}$$. Thus we need to find the value of x+y.

(1) The average of x and 2y is 10 --> $$\frac{x+2y}{2}=10$$. Not sufficient.

(2) The average of 2x and 7y is 32 --> $$\frac{2x+7y}{2}=32$$. Not sufficient.

(1)+(2) We have two distinct linear equations with two unknowns, thus we can solve for both and get the value of x+y. Sufficient.

_________________
Intern
Joined: 16 Mar 2014
Posts: 5
Re: What is the average (arithmetic mean) of x and y?  [#permalink]

### Show Tags

16 Mar 2015, 16:19
Just a quick question somewhat related to this problem:

When you're asked for x+y, is it safe to assume that you need either x and y individually, or the value of x+y combined to achieve sufficiency? Will things like x+2y, 3x+4y, etc. always be insufficient? Whenever I'm faced with these problems, I find myself spending time trying to manipulate the x+2y into x+y, so it would be nice to know if I could just quickly say insufficient and move on.
Non-Human User
Joined: 09 Sep 2013
Posts: 9121
Re: What is the average (arithmetic mean) of x and y?  [#permalink]

### Show Tags

05 Aug 2018, 11:18
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.
_________________
Re: What is the average (arithmetic mean) of x and y? &nbs [#permalink] 05 Aug 2018, 11:18
Display posts from previous: Sort by