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

 It is currently 12 Nov 2019, 12:48 ### 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

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # The length, breadth and height of a room are in the ratio 3:2:1. If th

Author Message
TAGS:

### Hide Tags

Intern  Joined: 20 May 2012
Posts: 15
Concentration: General Management, Finance
GRE 1: Q168 V162 GPA: 3.82
WE: Research (Health Care)
The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

4
8 00:00

Difficulty:   85% (hard)

Question Stats: 54% (02:28) correct 46% (02:41) wrong based on 208 sessions

### HideShow timer Statistics

The length, breadth and height of a room are in the ratio 3:2:1. If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%

Source: Gmat Cat By Nill (Peterson)

Originally posted by GMATnavigator on 21 Jul 2015, 10:52.
Last edited by Bunuel on 26 Nov 2018, 07:20, edited 2 times in total.
CEO  D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2978
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

3
2
GMATnavigator wrote:
The length, breadth and height of a room are in the ratio 3 : 2 : 1. If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%

Source: Gmat Cat By Nill (Peterson)

Let, Initially
Length (L) = 6
Height (H) = 2
Total Area of Walls = 2(BH + LH) = 2*(4*2 + 6*2) = 2*(8+12) = 40

Then, Finally
Length (L) = 2*6 = 12
Breadth (B) = 4/2 = 2
Height (H) = 2/2 = 1
Total Area of Walls = 2(BH + LH) = 2*(2*1 + 12*1) = 2*(2+12) = 28

% change in Area of four walls = (Final Area - Initial Area)*100 / Initial Area

i.e. % change in Area of four walls = (28 - 40)*100 /40 = - 30% (Decrease)

_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
##### General Discussion
Manager  Joined: 29 May 2013
Posts: 96
Location: India
Concentration: Technology, Marketing
WE: Information Technology (Consulting)
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

1
GMATinsight wrote:
GMATnavigator wrote:
The length, breadth and height of a room are in the ratio 3 : 2 : 1. If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%

Source: Gmat Cat By Nill (Peterson)

Let, Initially
Length (L) = 6
Height (H) = 2
Total Area of Walls = 2(BH + LH) = 2*(4*2 + 6*2) = 2*(8+12) = 40

Then, Finally
Length (L) = 2*6 = 12
Breadth (B) = 4/2 = 2
Height (H) = 2/2 = 1
Total Area of Walls = 2(BH + LH) = 2*(2*1 + 12*1) = 2*(2+12) = 28

% change in Area of four walls = (Final Area - Initial Area)*100 / Initial Area

i.e. % change in Area of four walls = (28 - 40)*100 /40 = - 30% (Decrease)

Hi GMATInsight,

Are we not taking the surface area of a rectangular box? in which case, the formula to calculate the surface area is 2(LH+BH+LB)?
Intern  Joined: 20 May 2012
Posts: 15
Concentration: General Management, Finance
GRE 1: Q168 V162 GPA: 3.82
WE: Research (Health Care)
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

1
jayanthjanardhan wrote:
GMATinsight wrote:
GMATnavigator wrote:
The length, breadth and height of a room are in the ratio 3 : 2 : 1. If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%

Source: Gmat Cat By Nill (Peterson)

Let, Initially
Length (L) = 6
Height (H) = 2
Total Area of Walls = 2(BH + LH) = 2*(4*2 + 6*2) = 2*(8+12) = 40

Then, Finally
Length (L) = 2*6 = 12
Breadth (B) = 4/2 = 2
Height (H) = 2/2 = 1
Total Area of Walls = 2(BH + LH) = 2*(2*1 + 12*1) = 2*(2+12) = 28

% change in Area of four walls = (Final Area - Initial Area)*100 / Initial Area

i.e. % change in Area of four walls = (28 - 40)*100 /40 = - 30% (Decrease)

Hi GMATInsight,

Are we not taking the surface area of a rectangular box? in which case, the formula to calculate the surface area is 2(LH+BH+LB)?

Hi,
@Jayantijanardan,

I think question only asks for the walls in the question in which case, we should not account for the ceiling and the floor. So, i think GMATinsight approach is right!
Correct me experts if i am wrong!

Give kudos if you like!
CEO  D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2978
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

1
jayanthjanardhan wrote:
GMATinsight wrote:
GMATnavigator wrote:
The length, breadth and height of a room are in the ratio 3 : 2 : 1. If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%

Source: Gmat Cat By Nill (Peterson)

Let, Initially
Length (L) = 6
Height (H) = 2
Total Area of Walls = 2(BH + LH) = 2*(4*2 + 6*2) = 2*(8+12) = 40

Then, Finally
Length (L) = 2*6 = 12
Breadth (B) = 4/2 = 2
Height (H) = 2/2 = 1
Total Area of Walls = 2(BH + LH) = 2*(2*1 + 12*1) = 2*(2+12) = 28

% change in Area of four walls = (Final Area - Initial Area)*100 / Initial Area

i.e. % change in Area of four walls = (28 - 40)*100 /40 = - 30% (Decrease)

Hi GMATInsight,

Are we not taking the surface area of a rectangular box? in which case, the formula to calculate the surface area is 2(LH+BH+LB)?

Question stem says " the total area of the four walls of the room will be???" Walls don't include the top and bottom surface with each area = L*B

I hope it helps!
_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
Manager  Joined: 08 Sep 2010
Posts: 56
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

GMATnavigator wrote:
The length, breadth and height of a room are in the ratio 3 : 2 : 1. If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%

Give Kudos if you like this question Source: Gmat Cat By Nill (Peterson)

Definitely not a 700 level question.
Solution:
Initial dimension:
length = 3x, breadth = 2x, height = x
Area of four walls = 2*(l+b)*h = 2(3x+2x)*x = 10x^2

New Dimension:
length = 6x, breadth = x, height = x/2
Area of four walls = 2*(6x+x)*x/2 = 7x^2

% change = (new area - old area) / old area = [(7x^2 - 10x^2) / 10x^2 ] * 100 = -30%. Hence option E i.e. decrease by 30%
Board of Directors P
Joined: 17 Jul 2014
Posts: 2497
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30 GPA: 3.92
WE: General Management (Transportation)
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

well...damn...what a tricky one...I calculated to have 13.++ % decrease, but this is including top and bottom. balls...
Intern  B
Joined: 23 Jul 2015
Posts: 35
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

You are finding the surface area of the 4 walls. Not all 6 faces (no ceiling and floor) and not the volume area.

Surface area of first is 2+2+3+3 = 10
Surface area of second is 3+3+(1/2)+(1/2) = 7

10 to 7 is a 30% decrease
Board of Directors P
Joined: 17 Jul 2014
Posts: 2497
Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30 GPA: 3.92
WE: General Management (Transportation)
Re: The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

4 walls = bh - hl - hl - bh so 2(bh+hl)
suppose l=30, b=20, h=10. total area = 2(200+300) = 1000
new lengths:
l=60, b=10, h=5. total area = 2(50+300) = 700.
decrease 300
300/1000 = 0.3 * 100% = 30% decrease
SVP  P
Joined: 03 Jun 2019
Posts: 1836
Location: India
The length, breadth and height of a room are in the ratio 3:2:1. If th  [#permalink]

### Show Tags

GMATnavigator wrote:
The length, breadth and height of a room are in the ratio 3:2:1. If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

(a) remain the same
(b) decrease by 13.64%
(c) decrease by 15%
(d) decrease by 18.75%
(e) decrease by 30%

Source: Gmat Cat By Nill (Peterson)

Given: The length, breadth and height of a room are in the ratio 3:2:1. The breadth and height are halved while the length is doubled.

Asked: Total area of the four walls of the room will

The length, breadth and height of a room are in the ratio 3:2:1.
Let The length, breadth and height of a room be 3x, 2x & x respectively
Total area of the four walls of the room = 2 (3x*x + 2x*x) = 10x^2

The breadth and height are halved while the length is doubled.
The length, breadth and height of a room change to 6x, x & x/2 respectively
Total area of the four walls of the room =$$2 (6x*x/2 + x*x/2) = 7x^2$$

Change in area of the four walls = (7-10)/10 = -3/10 (30% decrease)

IMO E
_________________
"Success is not final; failure is not fatal: It is the courage to continue that counts."

Please provide kudos if you like my post. Kudos encourage active discussions.

My GMAT Resources: -

Efficient Learning
All you need to know about GMAT quant

Tele: +91-11-40396815
Mobile : +91-9910661622
E-mail : kinshook.chaturvedi@gmail.com The length, breadth and height of a room are in the ratio 3:2:1. If th   [#permalink] 12 Aug 2019, 01:43
Display posts from previous: Sort by

# The length, breadth and height of a room are in the ratio 3:2:1. If th  