easyseries#1

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sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Wed Mar 24, 2010 6:09 am

The mind is everything. What you think you become. -Lord Buddha

Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com

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Source: Beat The GMAT — Data Sufficiency | Wed Mar 24, 2010 6:09 am

neoreaves: Master | Next Rank: 500 Posts; Posts: 208; Joined: Sun Sep 28, 2008 12:30 pm; Thanked: 22 times

by neoreaves » Wed Mar 24, 2010 6:42 am

Lets side of square = x
Let sides of rectange = a,b

x^2 = a.b

What we need to find = 4x (perimeter of square)

1) x^2 = 2x.b

Insufficient

2) x^2 = 36
x = 6
4x = 24

Sufficient

IMO Answer is B

Last edited by neoreaves on Wed Mar 24, 2010 9:24 am, edited 1 time in total.

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rockeyb: Legendary Member; Posts: 537; Joined: Sun Jul 19, 2009 7:15 amFollowed by: 1 member; Location: Nagpur , India; Thanked: 41 times

by rockeyb » Wed Mar 24, 2010 8:11 am

neoreaves wrote:Lets side of square = x
Let sides of rectange = a,b

x^2 = a.b

What we need to find = 4x (perimeter of square)

1) x^2 = 2x.b

Insufficient

2) x^2 = 36
x = 6
4x = 24

Sufficient

IMO Answer is A

I think you wanted to write B and NOT A .

"Know thyself" and "Nothing in excess"

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rockeyb: Legendary Member; Posts: 537; Joined: Sun Jul 19, 2009 7:15 amFollowed by: 1 member; Location: Nagpur , India; Thanked: 41 times

by rockeyb » Wed Mar 24, 2010 8:17 am

The area of square S is equal to the area of rectangle R. What is the perimeter of square S?

(1) The length of one of the sides of rectangle R is twice the length of a side of square S.

(2) The area of rectangle R is 36.

We need to find S ?

Statement (1): 2L = S (L = length of rectangle , B = breath of rectangle )

We know S^2 = L x B .

nothing is said about B . 2 unknown 1 equation can not be solved .

Not sufficient.

Statement (2) : Area of rectangle = 36 .

Area of rectangle = Area of square .

S^2 = 36

S = +/- 6 .

Not sufficient .

Combine (1) and (2).

Still not sufficient .

My take is E .

"Know thyself" and "Nothing in excess"

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neoreaves: Master | Next Rank: 500 Posts; Posts: 208; Joined: Sun Sep 28, 2008 12:30 pm; Thanked: 22 times

by neoreaves » Wed Mar 24, 2010 9:27 am

rockeyb wrote:The area of square S is equal to the area of rectangle R. What is the perimeter of square S?

(1) The length of one of the sides of rectangle R is twice the length of a side of square S.

(2) The area of rectangle R is 36.

We need to find S ?

Statement (1): 2L = S (L = length of rectangle , B = breath of rectangle )

We know S^2 = L x B .

nothing is said about B . 2 unknown 1 equation can not be solved .

Not sufficient.

Statement (2) : Area of rectangle = 36 .

Area of rectangle = Area of square .

S^2 = 36

S = +/- 6 .

Not sufficient .

Combine (1) and (2).

Still not sufficient .

My take is E .

I still think its B ....side of a square can never be negative so it should be B

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rockeyb: Legendary Member; Posts: 537; Joined: Sun Jul 19, 2009 7:15 amFollowed by: 1 member; Location: Nagpur , India; Thanked: 41 times

by rockeyb » Wed Mar 24, 2010 9:42 am

@neoreaves mate ,

A valid point . But are we trying to solve the problem .

OR

Are we asked to check if the data provided is sufficient to solve ?

The question to ask is "Do we really need to get to the final answer OR knowing just that we can is sufficient ?"

"Know thyself" and "Nothing in excess"

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neoreaves: Master | Next Rank: 500 Posts; Posts: 208; Joined: Sun Sep 28, 2008 12:30 pm; Thanked: 22 times

by neoreaves » Wed Mar 24, 2010 9:56 am

I think I have seen questions like these before. The standard way is to see if it is logical to have a negative value or not. Anyways lets see what the OA is and let that be the decider. So please post the OA and it would help if you can mention the source too.

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boazkhan: Master | Next Rank: 500 Posts; Posts: 135; Joined: Tue Oct 13, 2009 10:27 am; Thanked: 3 times

by boazkhan » Wed Mar 24, 2010 10:08 am

IMO E --- WHAT IS THE OA?

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sanju09: GMAT Instructor; Posts: 3650; Joined: Wed Jan 21, 2009 4:27 amFollowed by: 80 members; Location: India; Thanked: 267 times; GMAT Score:760

by sanju09 » Thu Mar 25, 2010 1:03 am

Once the stem of question, or any part of a DS question on GMAT confirms that we have to consider a geometric shape or something that has a non-zero/non-negativity constraint, we must not consider the negative possibilities in the solutions. I didn't bother to collect its OA though, but IMO [spoiler]B[/spoiler].

The mind is everything. What you think you become. -Lord Buddha

Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com

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harshavardhanc: Legendary Member; Posts: 526; Joined: Sat Feb 21, 2009 11:47 pm; Location: India; Thanked: 68 times; GMAT Score:680

by harshavardhanc » Thu Mar 25, 2010 1:19 am

rockeyb wrote:@neoreaves mate ,

A valid point . But are we trying to solve the problem .

OR

Are we asked to check if the data provided is sufficient to solve ?

The question to ask is "Do we really need to get to the final answer OR knowing just that we can is sufficient ?"

rockeyb,

I don't know why this happens....but it happens every time! coincidence!

the question just says that the area (enclosed within some boundary) is 36.

It's the formula / the way you are looking at this information, which is giving a negative value and which, as said by Sanju and neoreaves, should not be considered in cases of lengths of geometric figures?

Think about it : What does it mean if you say a square has side = -6 units? Does it make any sense?

As far as your question is concerned,

The question to ask is "Do we really need to get to the final answer OR knowing just that we can is sufficient ?"

we DON'T have to do any calculation. We just have to tell, based on the info, whether we can find the side or not?

Hence, B is sufficient to answer this question.

Regards,
Harsha

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rockeyb: Legendary Member; Posts: 537; Joined: Sun Jul 19, 2009 7:15 amFollowed by: 1 member; Location: Nagpur , India; Thanked: 41 times

by rockeyb » Thu Mar 25, 2010 3:29 am

Thanks very much guys ,

That a mistake I will surely remember and hope not to make the same one again .

Cheers !!!!!

"Know thyself" and "Nothing in excess"

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