BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

GMATPrerp DS

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 891
Joined: Sat Aug 16, 2008 4:21 am
Thanked: 27 times
Followed by:1 members
GMAT Score:660(

GMATPrerp DS

by 4meonly » Mon Dec 01, 2008 1:08 am
Image

OA is A


I marked correct answer using plug-ins, however, I need more scientific approach.

(1)
we have set of either odd or even nubers.
By testing
1-3-5-7-9 I got average=median
1-3-5-7 I got average=median
The same was with even numbers. I suppose that the same will be is I take not integers with difference equal to 2.
SUFF

(2)
Means that the range is even, so 1st and the last numbers both are either odd or even. But we dont know anything about other numbers in the set - they can be odd, even and not integers.
INSUFF

Anybody with more strong reasoning?
Last edited by 4meonly on Mon Dec 01, 2008 2:59 am, edited 1 time in total.
Top
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 2134
Joined: Mon Oct 20, 2008 11:26 pm
Thanked: 237 times
Followed by:25 members
GMAT Score:730

Re: GMATPrerp DS

by logitech » Mon Dec 01, 2008 1:29 am
4meonly wrote:Image

OA is A


I marked correct answer using plug-ins, however, I need more scientific approach.

(1)
we have either set of odd or even nubers.
By testing
1-3-5-7-9 I got average=median
1-3-5-7 I got average=median
The same was with even numbers. I suppose that the same will be is I take not integers with difference equal to 2.
SUFF

(2)
Means that the range is even, so 1st and the last numbers both are either odd or even. But we dont know anything about other numbers in the set - they can be odd, even and not integers.
INSUFF

Anybody with more strong reasoning?
Statement 1)

Evenly spaced consecutive numbers.

Mean and Median is same for any consecutive numbers set. SUF

Statement 2)

Even range gives us no information.

2(n-1) = 2n - 2

So first term is 2 and the nth term is 2n but we have no idea whats going in between

2 5 6 where n=3 and 2n=6

2 3 6 where n=3 and 2n=6
LGTCH
---------------------
"DON'T LET ANYONE STEAL YOUR DREAM!"
Top
Legendary Member
Posts: 891
Joined: Sat Aug 16, 2008 4:21 am
Thanked: 27 times
Followed by:1 members
GMAT Score:660(

Re: GMATPrerp DS

by 4meonly » Mon Dec 01, 2008 2:58 am
logitech wrote: Statement 2)
Even range gives us no information.
2(n-1) = 2n - 2
So first term is 2 and the nth term is 2n
thanx
i overlooked this
Top
Master | Next Rank: 500 Posts
Posts: 207
Joined: Sun Mar 11, 2007 6:16 pm
Location: Mumbai
Thanked: 11 times

Re: GMATPrerp DS

by jimmiejaz » Mon Dec 01, 2008 4:18 am
logitech wrote:
4meonly wrote:Image

OA is A


I marked correct answer using plug-ins, however, I need more scientific approach.

(1)
we have either set of odd or even nubers.
By testing
1-3-5-7-9 I got average=median
1-3-5-7 I got average=median
The same was with even numbers. I suppose that the same will be is I take not integers with difference equal to 2.
SUFF

(2)
Means that the range is even, so 1st and the last numbers both are either odd or even. But we dont know anything about other numbers in the set - they can be odd, even and not integers.
INSUFF

Anybody with more strong reasoning?
Statement 1)

Evenly spaced consecutive numbers.

Mean and Median is same for any consecutive numbers set. SUF

Statement 2)

Even range gives us no information.

2(n-1) = 2n - 2

So first term is 2 and the nth term is 2n but we have no idea whats going in between

2 5 6 where n=3 and 2n=6

2 3 6 where n=3 and 2n=6
logitech,
I also overlooked this part. Thanks for the expln though.....

Bro,

Mean and median 'are'. We have to keep a check on this. :)
What if i have not yet beat the beast, I know i will beat it!!!!!!!!
Top
Legendary Member
Posts: 2467
Joined: Thu Aug 28, 2008 6:14 pm
Thanked: 331 times
Followed by:11 members

by cramya » Mon Dec 01, 2008 6:09 am
I think we can generalize and say mean and median are the same for an a set whose common difference between successive(after arranging them in ascending) elements are the same

Consecutive numbers
Consecutive even integers
Consecutive odd integers

(OR)

0 100 200 300 400 COMMON DIFFERENCE - 100

I am thinking if we can say for an arithmetic progression(where the common difference is the same) the mean is the median. Feedback welcome and someone correct me if this generalization will not work!

Thus stmt I is sufficient


Stmt II

Picking numbers is the safest route to disprove this

0 2 4 6 8 Range 2(n-1) and mean = median

0 1 3 5 8 Range = 2(n-1) and mean not equal to median

INSUFF

A)
Top
Legendary Member
Posts: 708
Joined: Sun Jun 01, 2008 4:59 am
Location: USA
Thanked: 13 times
Followed by:1 members

by niraj_a » Mon Dec 01, 2008 7:18 am
AH

for statement 2, i pluggd in successive values for n and the range always moved by 2 so i thought B was sufficient too. fell for the trap.
Top
Post new topic Post Reply
• Page 1 of 1