It is currently 18 Nov 2017, 12:50

### 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 June
Open Detailed Calendar

# 50% of the aparments in a certain building have windows and

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

### Hide Tags

Current Student
Joined: 29 Jan 2005
Posts: 5201

Kudos [?]: 437 [2], given: 0

50% of the aparments in a certain building have windows and [#permalink]

### Show Tags

25 Nov 2005, 09:43
2
KUDOS
16
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

63% (02:20) correct 37% (02:05) wrong based on 483 sessions

### HideShow timer Statistics

50% of the apartments in a certain building have windows and hardwood floors. 25% of the apartments without windows have hardwood floors. If 40% of the apartments do not have hardwood floors, what percent of the apartments with windows have hardwood floors?

A. 10
B. 16 2/3
C. 40
D. 50
E. 83 1/3
[Reveal] Spoiler: OA

Kudos [?]: 437 [2], given: 0

VP
Joined: 30 Sep 2004
Posts: 1480

Kudos [?]: 425 [0], given: 0

Location: Germany

### Show Tags

25 Nov 2005, 10:04
83 1/3...best way is to construct a matrix...

..........h......no h....total
w.......50..................
no w..0,25x............x
total............40......100

fill in...
_________________

If your mind can conceive it and your heart can believe it, have faith that you can achieve it.

Kudos [?]: 425 [0], given: 0

SVP
Joined: 28 May 2005
Posts: 1699

Kudos [?]: 480 [0], given: 0

Location: Dhaka

### Show Tags

25 Nov 2005, 15:38
yup you need to construct a matrix

X********| Windows'|No Windows'''| total
hardFl****'|50*****''|10*********'|60
Not hardFl*|10******|30*********'|40
Total*****|60******'|40*********'|100

so percent of the apartments with windows have hardwood floors = 50/60 *100

= 83 1/3

so E is the answer.[/u]
_________________

hey ya......

Kudos [?]: 480 [0], given: 0

Intern
Joined: 12 Sep 2009
Posts: 4

Kudos [?]: 5 [4], given: 2

Re: This one will test your skill for Overlapping Sets concept [#permalink]

### Show Tags

16 Sep 2009, 07:57
4
KUDOS
E. Is that the correct answer choice. Please post OA.

Here is my working...
a = total windows
b = total of no windows

HW = .5 (given in the problem statement)
(No W,H) = 0.25b
H = 0.6 (given in the problem statement)
No H = 0.4 (deduced as 1 -.06, but this is not needed to solve the problem)

HW + (No W,H) = 0.60
.5+0.25b = 0.60
b = 0.40
Therefore a = 1-b = 1-.40 = 0.60 (proportion of apartments with windows)

Therefore the desired proportion = (HW/a)*100 = (0.5/0.6) * 100 = 83.33% (E).

Goldgoldandgold, could you please confirm the answer.

Kudos [?]: 5 [4], given: 2

Manager
Joined: 10 Jul 2009
Posts: 125

Kudos [?]: 187 [3], given: 60

Location: Ukraine, Kyiv
Re: This one will test your skill for Overlapping Sets concept [#permalink]

### Show Tags

16 Sep 2009, 10:32
3
KUDOS
E. did it by simple picking numbers and creating a table. check this out.
Attachments

solution.xls [7 KiB]

_________________

Never, never, never give up

Kudos [?]: 187 [3], given: 60

VP
Status: There is always something new !!
Affiliations: PMI,QAI Global,eXampleCG
Joined: 08 May 2009
Posts: 1283

Kudos [?]: 286 [0], given: 10

Re: This one will test your skill for Overlapping Sets concept [#permalink]

### Show Tags

02 May 2011, 02:07
total apartments = 100
with windows and hardwoods = 50
without windows = 50

without windows but having hardwoods = 0.25 *50 = 12.25

12.25 + with windows and hardwoods = 60
with windows and hardwoods = 47.75

% = 47.75 / 50 > 50%
Hence E.
_________________

Visit -- http://www.sustainable-sphere.com/
Promote Green Business,Sustainable Living and Green Earth !!

Kudos [?]: 286 [0], given: 10

VP
Status: Far, far away!
Joined: 02 Sep 2012
Posts: 1120

Kudos [?]: 2365 [1], given: 219

Location: Italy
Concentration: Finance, Entrepreneurship
GPA: 3.8
Re: 50% of the aparments in a certain building have windows and [#permalink]

### Show Tags

04 Apr 2013, 15:50
1
KUDOS
Tagger wrote:
Still can't get the solution using the Double matrix

Take a look at the image.

X is the percentage of Non-Window, and we know that 25% of that number has Hardwood => 0.25x is in the cell (NW, H) and 0,75x is, of course, in the (NW, NH) cell.
($$0.25x+0.75x=x$$). The tot Hardwood is 60%, and is composed by the first row: $$50+0.25x=60$$ x=40. Ok, we have X, or the tot perc of NonWindows.
Now we know also that $$y+40%=100%$$ and clearly y = 60% => tot perc of W is 60%.This is composed by the cell [Window, Hardwood (50%)] and by the cell [Window, NonHardwood (that must be 10% since 50%+10%=60%)]

And now we have all the data we can have. To answer the question: "what percent of the apartments with windows have hardwood floors?" we must calculate the fraction (apartments with windows and hardwood floors [W,H])/(apartments with windows[W]) = $$\frac{50%}{60%}$$ = $$83 \frac{1}{3}$$

Hope it's clear
Attachments

matrix.png [ 2.63 KiB | Viewed 6776 times ]

_________________

It is beyond a doubt that all our knowledge that begins with experience.

Kant , Critique of Pure Reason

Tips and tricks: Inequalities , Mixture | Review: MGMAT workshop
Strategy: SmartGMAT v1.0 | Questions: Verbal challenge SC I-II- CR New SC set out !! , My Quant

Rules for Posting in the Verbal Forum - Rules for Posting in the Quant Forum[/size][/color][/b]

Kudos [?]: 2365 [1], given: 219

Intern
Joined: 10 Nov 2014
Posts: 14

Kudos [?]: 8 [0], given: 37

Location: United Kingdom
WE: Information Technology (Consulting)
50% of the aparments in a certain building have windows and [#permalink]

### Show Tags

29 Oct 2016, 07:32
GMATT73 wrote:
50% of the apartments in a certain building have windows and hardwood floors. 25% of the apartments without windows have hardwood floors. If 40% of the apartments do not have hardwood floors, what percent of the apartments with windows have hardwood floors?

A. 10
B. 16 2/3
C. 40
D. 50
E. 83 1/3

------------------

HI Bunuel,

Could you please help here with a quicker way to solve such problems.

I used the Double matrix but it still took me 3 mins or a few secs more. May be bcoz I was trying to be a bit careful/slow trying not to get lost by the question wording.

How can we solve such problems from Sets. Is Matrix the best way ?

Cheers!

Kudos [?]: 8 [0], given: 37

Math Expert
Joined: 02 Aug 2009
Posts: 5201

Kudos [?]: 5826 [0], given: 117

Re: 50% of the aparments in a certain building have windows and [#permalink]

### Show Tags

07 Sep 2017, 07:43
GMATT73 wrote:
50% of the apartments in a certain building have windows and hardwood floors. 25% of the apartments without windows have hardwood floors. If 40% of the apartments do not have hardwood floors, what percent of the apartments with windows have hardwood floors?

A. 10
B. 16 2/3
C. 40
D. 50
E. 83 1/3

Hi..

In this Q you can get your answer in 10 secs

50% of ALL (that is 100%) apartments have window and hardwood floors..

now we are looking at having BOTH as a % of THOSE having windows..
which will be MORE than 50%.
ONLY E is left

In form of equation-
$$\frac{Both}{W}>\frac{Both}{W+NW}.....\frac{Both}{W}>50%$$
W is house with windows
NW is houses without windows
ALL = W + NW

_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

Kudos [?]: 5826 [0], given: 117

Re: 50% of the aparments in a certain building have windows and   [#permalink] 07 Sep 2017, 07:43
Display posts from previous: Sort by

# 50% of the aparments in a certain building have windows and

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

 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®.