Range of integers ques

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mshameen: Junior | Next Rank: 30 Posts; Posts: 11; Joined: Tue Oct 12, 2010 3:24 am

by mshameen » Tue Feb 01, 2011 12:35 am

List K consists of 12 consecutive integers. If -4 is the least integer in the list K, what is the range of the positive integers in list K?
A) 5
B) 6
C) 7
D) 11
E) 12

Whats the answer?

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Source: Beat The GMAT — Problem Solving | Tue Feb 01, 2011 12:35 am

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Rahul@gurome: GMAT Instructor; Posts: 1179; Joined: Sun Apr 11, 2010 9:07 pmFollowed by: 88 members; Location: Milpitas, CA; Thanked: 447 times

by Rahul@gurome » Tue Feb 01, 2011 12:43 am

Note that we have been asked the range for positive integers in the list.
Range is the difference between maximum and minimum value.
The integers in the list are -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7.
The minimum positive value is 1 and the maximum positive value is 7.
So the range of positive integers is 7 - 1= 6.
The correct answer is B.

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mshameen: Junior | Next Rank: 30 Posts; Posts: 11; Joined: Tue Oct 12, 2010 3:24 am

by mshameen » Tue Feb 01, 2011 12:50 am

Thanks. I dont know why but to me it appeared that 0-7 so range should be 7. Anyway, thanks. 6 is what the right answer appears to be on the GMATPrep software.

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quaktar0004: Junior | Next Rank: 30 Posts; Posts: 11; Joined: Sat Jan 15, 2011 3:40 pm

by quaktar0004 » Tue Feb 01, 2011 6:54 am

Why isn't "0" included in this range? I too thought the answer should be 7: 7-0=7. Please advise.

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Rahul@gurome: GMAT Instructor; Posts: 1179; Joined: Sun Apr 11, 2010 9:07 pmFollowed by: 88 members; Location: Milpitas, CA; Thanked: 447 times

by Rahul@gurome » Tue Feb 01, 2011 6:53 pm

quaktar0004 wrote:Why isn't "0" included in this range? I too thought the answer should be 7: 7-0=7. Please advise.

The reason is that zero is considered neither positive or negative.
You have to take only the positive integers while calculating the range.

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Everest: Senior | Next Rank: 100 Posts; Posts: 35; Joined: Mon Jan 03, 2011 4:56 pmFollowed by: 1 member; Location: Calif; Thanked: 2 times

by Everest » Tue Feb 01, 2011 8:17 pm

let's define the set = -4, -3, -2, -1, 0, 1 , 2 ,3, 4, 5, 6, 7 (12 integers)

Number of positive integers are = 1 , 2 ,3, 4, 5, 6, 7 (0 is neither positive not negative)

Range = max - min = 7 -1 = 6

IMO B

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aleph777: Master | Next Rank: 500 Posts; Posts: 131; Joined: Fri Jun 18, 2010 10:19 am; Location: New York, NY; Thanked: 10 times

by aleph777 » Wed Feb 02, 2011 12:33 pm

I'm confused here... The range isn't inclusive? I counted 1 through 7, inclusive. But to find the range you simply take max - min?

Thanks!

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Rahul@gurome: GMAT Instructor; Posts: 1179; Joined: Sun Apr 11, 2010 9:07 pmFollowed by: 88 members; Location: Milpitas, CA; Thanked: 447 times

by Rahul@gurome » Wed Feb 02, 2011 6:44 pm

aleph777 wrote:I'm confused here... The range isn't inclusive? I counted 1 through 7, inclusive. But to find the range you simply take max - min?

Thanks!

You don't have to take the number of elements between 1 and 7 inclusive.
You have to take the difference between maximum positive value which is 7 and minimum positive value which is 1.
This comes out to be 6.

Rahul Lakhani
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On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
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