Evenly spaced integers : Input needed

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mriyaz: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Sat Oct 03, 2009 4:15 am; Location: Hyderabad,India

Evenly spaced integers : Input needed

by mriyaz » Fri Oct 09, 2009 10:41 pm

Hello all,

Please discuss the solution to the following DS question.
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What is the sum of 5 evenly spaced integers in a set?

(1)The median of the set of numbers is 0.
(2)The range of the numbers in the set is 4.

Statement (1) BY ITSELF is sufficient, but statement (2) by itself is not sufficient.
Statement (2) BY ITSELF is sufficient, but statement (1) by itself is not sufficient.
Both statements TAKEN TOGETHER are sufficient, but NEITHER statement BY ITSELF is sufficient.
EACH statement BY ITSELF is sufficient.
The two statements TAKEN TOGETHER are NOT sufficient.

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Source: Beat The GMAT — Data Sufficiency | Fri Oct 09, 2009 10:41 pm

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pm; Location: Vancouver, BC; Thanked: 5254 times; Followed by:1268 members; GMAT Score:770

Re: Evenly spaced integers : Input needed

by Brent@GMATPrepNow » Sat Oct 10, 2009 7:19 am

mriyaz wrote:Hello all,

Please discuss the solution to the following DS question.
-----------------------------------------------------
What is the sum of 5 evenly spaced integers in a set?

(1)The median of the set of numbers is 0.
(2)The range of the numbers in the set is 4.

Statement (1) BY ITSELF is sufficient, but statement (2) by itself is not sufficient.
Statement (2) BY ITSELF is sufficient, but statement (1) by itself is not sufficient.
Both statements TAKEN TOGETHER are sufficient, but NEITHER statement BY ITSELF is sufficient.
EACH statement BY ITSELF is sufficient.
The two statements TAKEN TOGETHER are NOT sufficient.

(1) When we have an odd number of values (5 in this case) the median will be the value of the middle number. So, here the middle number of the 5 numbers must be 0.
This means, two numbers are greater than 0 and two numbers are less than 0.
Since the numbers are evenly spaced, the two positive values will have the same magnitude as the two negative numbers.
e.g., -2, -1, 0, 1, 2 or -10, -5, 0, 5, 10 etc
As you can see, the sum of the 5 numbers will always be zero. So, statement (1) is SUFFICIENT

(2) Two conflicting sets of numbers:
1, 2, 3, 4, 5 --> sum = 15
0, 1, 2, 3, 4 --> sum = 10
INSUFFICIENT

Answer = A

Brent Hanneson - Creator of GMATPrepNow.com

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imanemekouar: Junior | Next Rank: 30 Posts; Posts: 10; Joined: Wed Dec 16, 2009 6:39 am

by imanemekouar » Mon Dec 28, 2009 7:06 am

in number 2 :1,2,3,4,5 are not evenly spaced integer? so the reasoning is not correct. Correct me if i m wrong.

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papgust: Community Manager; Posts: 1537; Joined: Mon Aug 10, 2009 6:10 pm; Thanked: 653 times; Followed by:252 members

by papgust » Mon Dec 28, 2009 7:55 am

1,2,3,4,5 is the sequence of evenly spaced integers. Even spaced integers are nothing but the sequence of integers must have the same difference consecutively. Here, difference is 1 throughout the sequence. So, they are evenly spaced integers