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How much wallpaper is needed to cover the two largest walls of a narrow room that is 9 feet high?
(1) The room is 10 feet wide.
(2) The room is 24 feet long.
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(1) The room is 10 feet wide.
(2) The room is 24 feet long.
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
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Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.
How much wallpaper is needed to cover the two largest walls of a narrow room that is 9 feet high?
(1) The room is 10 feet wide.
(2) The room is 24 feet long.
In the original condition, there are 4 variables(length and width of the wall, length and width of the wall paper), which should match with the number of equations. So you need 4 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make E the answer.
When 1) & 2), you cannot figure out length and width of the wall paper, which is not sufficient.
Therefore, the answer is E.
-> For cases where we need 3 more equations, such as original conditions with “3 variables”, or “4 variables and 1 equation”, or “5 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 80% chance that E is the answer (especially about 90% of 2 by 2 questions where there are more than 3 variables), while C has 15% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since E is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, C or D.
How much wallpaper is needed to cover the two largest walls of a narrow room that is 9 feet high?
(1) The room is 10 feet wide.
(2) The room is 24 feet long.
In the original condition, there are 4 variables(length and width of the wall, length and width of the wall paper), which should match with the number of equations. So you need 4 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make E the answer.
When 1) & 2), you cannot figure out length and width of the wall paper, which is not sufficient.
Therefore, the answer is E.
-> For cases where we need 3 more equations, such as original conditions with “3 variables”, or “4 variables and 1 equation”, or “5 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 80% chance that E is the answer (especially about 90% of 2 by 2 questions where there are more than 3 variables), while C has 15% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since E is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, C or D.
Bunuel
Height of Room = 9 feet
Bigger dimension of Length and width is needed to find the area of biggest walls to find the amount of wallpaper needed to cover them
Question : What is the length of bigger dimension of length and width of room ?
Statement 1: The room is 10 feet wide.
The other dimension i.e. length is not available to find which one is bigger and what's the dimension of bigger dimension of room. Hence
NOT SUFFICIENT
Statement 2: The room is 24 feet long.
The other dimension i.e. length is not available to find which one is bigger and what's the dimension of bigger dimension of room. Hence
NOT SUFFICIENT
Combining the two statements
L= 24 and b = 10
i.e. Longer dimension is 24
Height = 9
Area of biggest wall = L*H = 24*9
Since we have area, Hence
SUFFICIENT
Answer: option C
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MathRevolution
I feel that the question asking "How much wall paper" means what's the area of wallpaper needed to cover the biggest walls.
We don't need Length and width of wallpaper because questions is not asking "How many rectangular wallpapers are needed" which would have required the dimensionsof rectangular wall paper
Also your explanation seems to be assuming that wallpaper is rectangular whereas nowhere is it mentioned and as oer RULES of GMAT we can't assume anything.
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Himanshu1309
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Wallpaper dimensions are not given. Both the statements will not suffice to give the required answer.
Shouldn't the answer be B. It's a narrow room. Therefore, wallpaper required will be 2x24x9.
visver
visver,
B will not be the answer because you know that length is 24 but you don't know what is width.
P.S.Width is not essentially smaller than length i.e. The biggest wall may have area = width*9 as well
Himanshu1309,
Which dimension of wallpaper are you expecting???
Please read my above mentioned comments in this thread. The questions does not ask "How MANY wallpaper" instead questions is asking "Hoe MUCH wallpaper is required?" and the amount of wall paper required to cover will be equal to the area of biggest walls so we don't require dimensionsof wallpaper.
I hope this helps!
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Bunuel
Hi,
I may go against all the replies given on top on the basis of meaning of each word..
the definition of LENGTH as per OXFORD or other dictionaries is
LENGTH:- The measurement or extent of something from end to end; the greater of two or the greatest of three dimensions of an object
Now since we are talking of walls and height is already given as 9 feet, and also its a narrow room meaning legth and width are not the same,
so we require to know the length to find the area of largest walls..
lets see the statements:-
(1) The room is 10 feet wide.
this is the smaller wall and we are looking for the largest wall
Insuff..
(2) The room is 24 feet long.
this gives us the length, so the area of largest walls = 24*9..
and we require 2ice of that..
suff
ans B
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vivekkumar987
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I like to go with cheetanu
Largest side will be related to length and not the width, hence B is sufficient
Largest side will be related to length and not the width, hence B is sufficient
chetan2u
It's interesting to see the definition however I am confident that GMAT can't expect test taker to get confused with the definition of "length" so let's see the official answer.
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GMATinsight
======================
Sorry, I misread the question. Since the question doesn't say price, there are 3 variables(length, width, unit price of wall paper).
Therefore, the answer is E.
mikeonbike
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I am sorry... But am I missing something here.... 
I answered E because the question doesn't say its a rectangular room... ?
Is that correct? or there's a convention with GMAT that rooms can always be assumed to be rectangular?
I answered E because the question doesn't say its a rectangular room... ?Is that correct? or there's a convention with GMAT that rooms can always be assumed to be rectangular?
Question asks wallpaper needed to cover the largest walls of the room.
Largest walls would be the walls associated with length of the room.(Length > width)
We know the height of the room.
Statement 1: Gives only width. so we cant find the area of larger walls. So not sufficient
Statement 2: Gives length. Question gives height of the room. Hence we can find the area the largest walls. So 2 alone is sufficient
Hence B
Largest walls would be the walls associated with length of the room.(Length > width)
We know the height of the room.
Statement 1: Gives only width. so we cant find the area of larger walls. So not sufficient
Statement 2: Gives length. Question gives height of the room. Hence we can find the area the largest walls. So 2 alone is sufficient
Hence B
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