GMAT Data Sufficiency Discussions

[Dopa]

Originally Posted by srikanth267

I remember q1 from OG where i had differed frm option C n here goes my explanation why i chose A
Statement 1 says that all sides of the hexagon are equal.....which means the figure is a regular hexagon, whose each interior angle = 120 deg
Hence diagonals of this hexagon bisect the angle and 6 triangles are formed, whose each angle = 60 deg
Hence all 6 triangles are equilateral.

Statement 2: Each diagonal bisects each other....=>does not say anything about the sides of the figure n hence is not sufficient.

OA is A
i cud nt understand the explanation either...if any of u cud explain i'll be very grateful

q2) Is it a-IbI<a-b or a · |b| < a – b,,,I mean the operative on LHS of the inequality is not clear.

thanks

1. Even I thought the same when I first attempted the hexagon question. A hexagon will be regular hexagon when its six sides and six angles are equal. Statement 1 only says that the hexagon has six equal sides, a distorted/streched hexagon can be drawn with six equal sides but they won't have equal angles. Hence (1) alone is not enough.
Statement 2 is not enough as we can draw a hexagon having unequal sides which will satisfy the criteria. So, (2) alone is also not enough.

Considering both options together gives us a regular hexagon, in which case the triangles will be equilateral. Hence answer is (C).

Hope it helps

2. The inequality is -> (a · |b|) < (a – b)
b is in modulus.

[*arch*]

Three segments are drawn from opposite corners of a hexagon to form six triangles.These segments all bisect each other at point A. Are all of the triangles equilateral?

1. all six sides of hexagon are the same length
2. the three segments drawn between the opposite corners are equal length.

For the question shown above, 800 score has given an explanation for why the answer must be option (C). The link for the explanation has been pasted below:-

Explanation for GMAT MATH Test 1 Question 25

[tishan]

Hi.....I am struk at a silly question from the OG 11..................
Is n an integer?1)n^2 is an inetezer2)n^1/2 is an intezer
2 proofs that n is an intezer...............so the ans is B.according to me the ans should be D.because n^2=n*n......so if n^2 is an intezer n has be be an intezer........puys please help me with my silly query...........thanks in advance

[ashishjha100]

Originally Posted by tishan

Hi.....I am struk at a silly question from the OG 11..................
Is n an integer?1)n^2 is an inetezer2)n^1/2 is an intezer
2 proofs that n is an intezer...............so the ans is B.according to me the ans should be D.because n^2=n*n......so if n^2 is an intezer n has be be an intezer........puys please help me with my silly query...........thanks in advance

consider the simple example let n^2=5

but n=2.24 .......so n not necesserily be an integer......

[tishan]

Originally Posted by ashishjha100

consider the simple example let n^2=5

but n=2.24 .......so n not necesserily be an integer......

ok...got it thanks...

[srikanth267]

Statement 1 says that n^2 is an int...it does not necessarily mean that n is also an integer...n^2 may be 37 but is square root is not an integer
Statement 2 says tht n^(1/2) is an int...defnitely n would also be an integer since square of a number is always an integer

Hence OA is B

thanks

[naveen_petrucci]

Help me out with this one guys


What is the volume of a certain rectangular solid?

(1) Two adjacent faces of the solid have areas 15 and
24, respectively

(2) Each of two opposite faces of the solid has an area of 40

[HellFreezer]

Originally Posted by naveen_petrucci

Help me out with this one guys


What is the volume of a certain rectangular solid?

(1) Two adjacent faces of the solid have areas 15 and
24, respectively

(2) Each of two opposite faces of the solid has an area of 40

IMO, (1) alone is sufficient to get the volume. As the adjacent faces have areas 15 & 24, the common side has to be 3. Hence the volume has to be 3 * 8 * 5.

(2) does not say anything about the individual sides neither about the area of the base (which of course is a square).

Hence, 1 alone is sufficient to get the volume of the rectangular solid.

[Dopa]

Originally Posted by naveen_petrucci

Help me out with this one guys


What is the volume of a certain rectangular solid?

(1) Two adjacent faces of the solid have areas 15 and
24, respectively

(2) Each of two opposite faces of the solid has an area of 40

Option - 1 : Two adjacent faces of the solid have areas 15 and 24, respectively. It means l.b = 15 and b.h = 24 where l,b,h are length, breadth and height respectivley of the rectangular solid.
One side is common to the adjacent faces whose areas we know. But, from this data we can't be sure as what's the exact l,b or h. Because there are more than one choices fit this solution such as l,b,h = [15,1,24] [5,3,8]

(You can take l.h also instead of l.b but that wont make any difference because ultimately we have to find l.b.h) Not sufficient.

Option - 2 : Each of two opposite faces of the solid has an area of 40. That means all the 6 faces have area = 40. Again, many possibiliteis. not sufficient.

Considering both option - A and B : They both contradict. Not sufficient.

Answer should be E.

What's the OA ?

[srikanth267]

Originally Posted by Dopa

Option - 1 : Two adjacent faces of the solid have areas 15 and 24, respectively. It means l.b = 15 and b.h = 24 where l,b,h are length, breadth and height respectivley of the rectangular solid.
One side is common to the adjacent faces whose areas we know. But, from this data we can't be sure as what's the exact l,b or h. Because there are more than one choices fit this solution such as l,b,h = [15,1,24] [5,3,8]

(You can take l.h also instead of l.b but that wont make any difference because ultimately we have to find l.b.h) Not sufficient.

Option - 2 : Each of two opposite faces of the solid has an area of 40. That means all the 6 faces have area = 40. Again, many possibiliteis. not sufficient.

Considering both option - A and B : They both contradict. Not sufficient.

Answer should be E.

What's the OA ?

15 = 3*5*1
24= 1*2^3*3

We get dff ordered sets for (l.b.h) as (3,5,, (1,15,24) not necessarily in the same order.

Hence 1 is not sufficient.

Statement 2: Area of two opposite faces = 40 is not sufficient to find the 3 sides of the cuboid.

Hence OA is E.

Dopa, I was about to choose E but then read ur post n realised tht there canbe also be another way of representing (l.b.h)