DS question : GMAT Data Sufficiency (DS)

DS question

Oldest

Best Reply

Author

Message

TAGS:

Senior Manager

Joined: 14 Jul 2005

Posts: 410

Followers: 1

Kudos [?]: 3 [0], given: 0

Re: DS question [#permalink]

13 Sep 2006, 21:48

00:00

Question Stats:

0% (00:00) correct

0% (00:00) wrong

based on 0 sessions

abraham421 wrote:

can anyone help me out with this?.....the answer is D:

25. The surface area of a square tabletop was changed so that one of the dimensions was reduced by 1 inch and the other dimension was increased by 2 inches. What was the surface area before these changes were made?
(1) After the changes were made, the surface area was 70 square inches.

Since it is a sqaretop, let side =x, Hence (x-1)(x+2)= 70

Solving you get x=8 SUFF

(2) There was a 25 percent increase in one of the dimensions.

Since there was a 1/4 increase, 1/4 * x = 2 i.e. x=8 SUFF

Hence D

Manager

Joined: 24 Oct 2005

Posts: 171

Followers: 17

Kudos [?]: 57 [0], given: 0

[#permalink]

14 Sep 2006, 11:59

I am a little confused. Can anyone clarify this basic concept for me:

(x-1)(x+2) = 70

x^2+x-72= 0

(x+9)(x-8) = 0

x = -9
x = 8

Since -9 is a negative number, we can say that is not a valid solution for the problem since we cannot have a "negative" side. Thus, making +8 the only solution. Is this correct or am I missing somthing? :roll:

Senior Manager

Joined: 03 Jul 2006

Posts: 482

Followers: 1

Kudos [?]: 1 [0], given: 0

[#permalink]

14 Sep 2006, 12:18

I thought it was C.

Couldn't 5x11 also be a solution for the original measurements, making 1 insufficient?

SVP

Joined: 05 Jul 2006

Posts: 1563

Followers: 4

Kudos [?]: 63 [0], given: 34

[#permalink]

15 Sep 2006, 01:22

The surface area of a square tabletop was changed so that one of the dimensions was reduced by 1 inch and the other dimension was increased by 2 inches. What was the surface area before these changes were made?
(1) After the changes were made, the surface area was 70 square inches.
(2) There was a 25 percent increase in one of the dimensions.

Original surface area = x^2 ( the only dimensions where x)

dimensions after change ( the table is no more a square) =

x-1 , x+2.... what is x???

from one the surface area = (x-1)(x+2) = 70

and since the only two factors of 70 with a difference of 3 (x+2 - x+1) are 7,10

ie x-1 = 7 and x+2 = 10 gives the same value of x and thus x = 8 ...suff

from two

st two is talking about increase thus those 25% increase is equall to the 2 inches increse thus x = 8

suff

my answer is D

Joined: 02 Jun 2006

Posts: 1278

Followers: 2

Kudos [?]: 15 [0], given: 0

[#permalink]

15 Sep 2006, 07:02

Answer: D

Let a = original dimension

S1 : New area = 70 = (a+1) (a-2)

Can solve.. sufficient.

S2:
Increase in one dimensio is 25%.

a+1 = 1.25a

Sufficient.

Answer: D

[#permalink] 15 Sep 2006, 07:02

	Similar topics	Author	Replies	Last post
Similar Topics:	DS question	lealexandre	2	08 Dec 2005, 01:25
	DS question	microjohn	16	03 Aug 2006, 18:43
	DS Question	lan583	1	04 Aug 2006, 14:09
	ds question	dipeshc4	4	05 Oct 2006, 14:08
	DS Question	vijay2001	1	15 Apr 2007, 19:37

DS question

Main navigation

GMAT Resources

Partners

MBA Resources

GMAT ® is a registered trademark of the Graduate Management Admission Council ® (GMAC ®). GMAT Club's website has not been reviewed or endorsed by GMAC.

GMAT Courses

Admissions Consulting

DS question

DS question

Main navigation

GMAT Resources

Partners

MBA Resources