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

 It is currently 17 Oct 2018, 18:14

### 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

# By what % did the median household income in country Y

Author Message
TAGS:

### Hide Tags

Manager
Joined: 10 Nov 2010
Posts: 196
Location: India
Concentration: Strategy, Operations
GMAT 1: 520 Q42 V19
GMAT 2: 540 Q44 V21
WE: Information Technology (Computer Software)
By what % did the median household income in country Y  [#permalink]

### Show Tags

14 Feb 2011, 00:25
1
4
00:00

Difficulty:

35% (medium)

Question Stats:

65% (01:08) correct 35% (01:26) wrong based on 273 sessions

### HideShow timer Statistics

By what % did the median household income in country Y decrease from 1970 to 1980?

(1) In 1970 the median household income in Country Y was 2/3 of the median household income in Country X
(2) In 1980 the median household income in Country Y was 1/2 of the median household income in Country X

Let median household income in Country Y is y
Let median household income in Country X is x

a) in 1970 y=2/3x
not sufficient
b) in 1980 y=1/2x
not sufficient

Combining a and b

%decrease = (1/2x-2/3x) /2/3x

C

But it is wrong

_________________

The proof of understanding is the ability to explain it.

Director
Status: -=Given to Fly=-
Joined: 04 Jan 2011
Posts: 801
Location: India
Schools: Haas '18, Kelley '18
GMAT 1: 650 Q44 V37
GMAT 2: 710 Q48 V40
GMAT 3: 750 Q51 V40
GPA: 3.5
WE: Education (Education)
Re: By what % did the median household income in country Y  [#permalink]

### Show Tags

14 Feb 2011, 00:53
3
Let the median income of country Y be y for 1970
Let the median income of country X be x for 1970

Let the median income of country Y be y' for 1980
Let the median income of country X be x' for 1980

Question: (y'-y)/y * 100 = ?

Statement 1:
In 1970, y = (2/3)x
It tells us nothing about y'
So, not sufficient

Statement 2:
y' = (1/2)x'
It tells us nothing about the relation with y

Both Statements Together:
y = (2/3)x
y' = (1/2)x'

Now, we have no way of equating the two data.
So Not sufficent

Ans: 'E'
_________________

"Wherever you go, go with all your heart" - Confucius

1. How to Review and Analyze your Mistakes (Post by BB at GMAT Club)

2. 4 Steps to Get the Most out out of your CATs (Manhattan GMAT Blog)

My Experience With GMAT

1. From 650 to 710 to 750 - My Tryst With GMAT

2. Quest to do my Best - My GMAT Journey Log

Director
Status: -=Given to Fly=-
Joined: 04 Jan 2011
Posts: 801
Location: India
Schools: Haas '18, Kelley '18
GMAT 1: 650 Q44 V37
GMAT 2: 710 Q48 V40
GMAT 3: 750 Q51 V40
GPA: 3.5
WE: Education (Education)
Re: By what % did the median household income in country Y  [#permalink]

### Show Tags

14 Feb 2011, 00:56
1
GMATD11 wrote:
Let median household income in Country Y is y
Let median household income in Country X is x

a) in 1970 y=2/3x
not sufficient
b) in 1980 y=1/2x
not sufficient

Combining a and b

%decrease = (1/2x-2/3x) /2/3x

C

But it is wrong

You can't assume that the median has remained unchanged from 70s to 80s
So you must assign different variables for the median in year 70 and 80 for both town X and Y!
_________________

"Wherever you go, go with all your heart" - Confucius

1. How to Review and Analyze your Mistakes (Post by BB at GMAT Club)

2. 4 Steps to Get the Most out out of your CATs (Manhattan GMAT Blog)

My Experience With GMAT

1. From 650 to 710 to 750 - My Tryst With GMAT

2. Quest to do my Best - My GMAT Journey Log

Retired Moderator
Joined: 20 Dec 2010
Posts: 1835
Re: By what % did the median household income in country Y  [#permalink]

### Show Tags

14 Feb 2011, 01:09
GMATD11 wrote:
91)By what % did the median household income in country Y decrease from 1970 to 1980?
a) In 1970 the median household income in Country Y was 2/3 of the median household income in Country X
b) In 1980 the median household income in Country Y was 1/2 of the median household income in Country X

Let median household income in Country Y is y
Let median household income in Country X is x

a) in 1970 y=2/3x
not sufficient
b) in 1980 $$\color{red}{y=1/2x}$$
not sufficient
"x" may not be median household income for country x in 1980. It could be (x+100) or (x-89) or (x*4.5)

Let's take some numbers;
1970:
Median income for x: 90
Median income for y = (2/3)*90 = 60

1980
Median income for x: 120
Median income for y = (1/2)*120 = 60

Percent decrease: 0%

case II:
1970:
Median income for x: 90
Median income for y = (2/3)*90 = 60

1980
Median income for x: 30
Median income for y = (1/2)*30 = 15

% decrease for y = 45/60*100 = 75%

Ans :"E"
_________________
Director
Status: -=Given to Fly=-
Joined: 04 Jan 2011
Posts: 801
Location: India
Schools: Haas '18, Kelley '18
GMAT 1: 650 Q44 V37
GMAT 2: 710 Q48 V40
GMAT 3: 750 Q51 V40
GPA: 3.5
WE: Education (Education)
Re: By what % did the median household income in country Y  [#permalink]

### Show Tags

14 Feb 2011, 01:13
1
The answer would have been C is some additional info was given in the main statement. Info like,

if the median for city x remained unchanged from 1970 to 1980, what is the percentage change in the value of the median for city y from 1970 to 1980.
_________________

"Wherever you go, go with all your heart" - Confucius

1. How to Review and Analyze your Mistakes (Post by BB at GMAT Club)

2. 4 Steps to Get the Most out out of your CATs (Manhattan GMAT Blog)

My Experience With GMAT

1. From 650 to 710 to 750 - My Tryst With GMAT

2. Quest to do my Best - My GMAT Journey Log

Director
Status: No dream is too large, no dreamer is too small
Joined: 14 Jul 2010
Posts: 514
Re: By what % did the median household income in country Y  [#permalink]

### Show Tags

14 Feb 2011, 06:45
both the options do not provide any clues of changing house hold income from 1970 to 1980.
_________________

Collections:-
PSof OG solved by GC members: http://gmatclub.com/forum/collection-ps-with-solution-from-gmatclub-110005.html
DS of OG solved by GC members: http://gmatclub.com/forum/collection-ds-with-solution-from-gmatclub-110004.html
100 GMAT PREP Quantitative collection http://gmatclub.com/forum/gmat-prep-problem-collections-114358.html
Collections of work/rate problems with solutions http://gmatclub.com/forum/collections-of-work-rate-problem-with-solutions-118919.html
Mixture problems in a file with best solutions: http://gmatclub.com/forum/mixture-problems-with-best-and-easy-solutions-all-together-124644.html

Math Expert
Joined: 02 Sep 2009
Posts: 49968
Re: By what % did the median household income in country Y  [#permalink]

### Show Tags

27 Aug 2014, 04:28
GMATD11 wrote:
By what % did the median household income in country Y decrease from 1970 to 1980?

(1) In 1970 the median household income in Country Y was 2/3 of the median household income in Country X
(2) In 1980 the median household income in Country Y was 1/2 of the median household income in Country X

Let median household income in Country Y is y
Let median household income in Country X is x

a) in 1970 y=2/3x
not sufficient
b) in 1980 y=1/2x
not sufficient

Combining a and b

%decrease = (1/2x-2/3x) /2/3x

C

But it is wrong

Similar question to practice: from-january-1-2002-to-july-1-2002-the-median-household-173769.html
_________________
Non-Human User
Joined: 09 Sep 2013
Posts: 8443
Re: By what % did the median household income in country Y  [#permalink]

### Show Tags

24 Nov 2017, 04:01
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: By what % did the median household income in country Y &nbs [#permalink] 24 Nov 2017, 04:01
Display posts from previous: Sort by