What is the median?

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ern5231: Master | Next Rank: 500 Posts; Posts: 226; Joined: Sun Aug 09, 2009 4:34 am

by ern5231 » Thu Sep 24, 2009 10:24 pm

There are 50 continuous integers in a series. What is the median of the series?

a) Max number is 25
b) Sum of the biggest and the smallest number is 1

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Source: Beat The GMAT — Problem Solving | Thu Sep 24, 2009 10:24 pm

engg.manik: Senior | Next Rank: 100 Posts; Posts: 65; Joined: Thu Jul 02, 2009 10:38 pm; Location: Bangalore; Thanked: 1 times

by engg.manik » Thu Sep 24, 2009 11:30 pm

If the max number is 25 then the series should be

from -24, -23 ,-22 ..... 0 , 1 , ...25.

It also satisfies the second condition min + max = 1.

Now the median will be (0 + 1)/ 2 = 0.5

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ern5231: Master | Next Rank: 500 Posts; Posts: 226; Joined: Sun Aug 09, 2009 4:34 am

by ern5231 » Fri Sep 25, 2009 4:05 am

This is a DS question. The OA given is D but I feel the answer is A.

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

Re: What is the median?

by Brent@GMATPrepNow » Fri Sep 25, 2009 6:35 am

ern5231 wrote:There are 50 continuous integers in a series. What is the median of the series?

a) Max number is 25
b) Sum of the biggest and the smallest number is 1

(a)From here we can determine that the numbers range from -24 to 25. Since we know all 50 numbers, we can determine the median --> SUFF

(b) let x = the smallest integer
x+1 = 2nd integer
x+2 = 3rd integer
.
.
.
x+49 = 50th (last) integer
From the statement we can write the equation x + (x+49)=1
We can solve this equation to get x=-24.
Now that we know the first number is -24, we can determine that the last number is 25.
Since we know all 50 numbers, we can determine the median --> SUFF

Answer=D

Brent Hanneson - Creator of GMATPrepNow.com

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ern5231: Master | Next Rank: 500 Posts; Posts: 226; Joined: Sun Aug 09, 2009 4:34 am

by ern5231 » Fri Sep 25, 2009 5:57 pm

Thanks Brent but suppose we have a series : -49 to 0 then the median is not the same as obtained above. In that case the again the answer should be A. Where am I going wrong?

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

by Brent@GMATPrepNow » Sat Sep 26, 2009 1:58 pm

ern5231 wrote:Thanks Brent but suppose we have a series : -49 to 0 then the median is not the same as obtained above. In that case the again the answer should be A. Where am I going wrong?

Are you suggesting that the set of numbers from -49 to 0 satisfy the condition set out in statement (2)?
Here, the sum of the biggest and smallest numbers is not 1

Brent Hanneson - Creator of GMATPrepNow.com

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