|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 19 Nov 2010
Posts: 93
Followers: 2
Kudos [?]:
38
[0], given: 9
|
When is the mean = median? [#permalink]
 24 May 2012, 13:04
From my understanding, mean = median if,
1. the set consists of evenly spaced numbers
2. if all the members of the set are equal
3. set has just one number
Is there any thing else? In DS type of "is mean = median" questions, what do you have to know to be sure that mean = median?
|
|
|
|
|
|
|
Manager
Joined: 21 May 2012
Posts: 53
Location: United States (CA)
Concentration: Marketing, Operations
Followers: 1
Kudos [?]:
12
[0], given: 0
|
Re: When is the mean = median? [#permalink]
24 May 2012, 20:17
Not true, here's an example where mean = median and none of your criteria listed are met.
{0,50,50,50,100}
For any evenly spaced set, the mean of the set is always equal to the median. But not vice versa!
Last edited by Cares on 24 May 2012, 21:13, edited 1 time in total.
|
|
|
|
|
|
Manager
Joined: 29 Mar 2012
Posts: 247
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 10
Kudos [?]:
52
[0], given: 20
|
Re: When is the mean = median? [#permalink]
24 May 2012, 20:54
bellcurve wrote: From my understanding, mean = median if,
1. the set consists of evenly spaced numbers
2. if all the members of the set are equal
3. set has just one number
Is there any thing else? In DS type of "is mean = median" questions, what do you have to know to be sure that mean = median? Hi, If a series is an arithmetic progression then mean value will always be equal to median, but vice versa is not true. Thus, any series can be formed other than the ones you have mentioned where mean = median.
_________________
My posts: Solving Inequalities, Solving Simultaneous equations, Divisibility Rules
My story: 640 What a blunder!
My page: Ed Prep
|
|
|
|
|
|
Manager
Joined: 19 Nov 2010
Posts: 93
Followers: 2
Kudos [?]:
38
[0], given: 9
|
Re: When is the mean = median? [#permalink]
25 May 2012, 06:44
Thanks guys!
I did not say that the list that I provided is the exhaustive list. I just wanted add more to it. So if the Q is "is mean=median" What constitute sufficiency other than arithmetic progression and/or evenly spaced sets? Anything about the relationship that can be expressed in terms of range, relationship between the smallest or largest number, or the relationship between median and other numbers etc.?
|
|
|
|
|
|
GMAT Pill Instructor
Joined: 14 Apr 2009
Posts: 891
Location: New York, NY
Followers: 79
Kudos [?]:
218
[0], given: 0
|
Re: When is the mean = median? [#permalink]
31 May 2012, 12:03
Perhaps the easiest way to understand when mean = median is this one reqiurement: 1) When the distribution above the mean is symmetrical to the distribution below the mean. So think of the middle point. Whatever pattern of data you have above the middle point is mirrored on the other side (below) the middle point. When this happens, the mean will effectively be the same as the median (the middle number by rank). This is satisfied when data is evenly spaced out. It's also true in other mirror-like cases. Sure the distribution does not necessarily have to be exactly mirrored on both sides. But as long as they roughly cancel each other out, then you'll have a situation where the mean = median.
_________________
      
... and more
Zeke Lee, GMAT Pill Study Method (Study Less. Score More.) | Download Ebook
- How A McKinsey Analyst Struggled with GMAT for 2 Yrs
- GMAT Score From 650 to 760 + 25 Minutes left on the exam! Wow!
GMAT Pill Reviews
|
|
|
|
|
|
Senior Manager
Joined: 15 Sep 2009
Posts: 272
GMAT 1: 750 Q V
Followers: 4
Kudos [?]:
34
[0], given: 6
|
Re: When is the mean = median? [#permalink]
05 Jun 2012, 05:42
Median=Mean when: 1) Numbers are in a sequence i.e. evenly spaced (and that includes consecutive numbers) 2) Only one item in the set 3) All members of the set are equal Cheers.
_________________
+1 Kudos me - I'm half Irish, half Prussian.
|
|
|
|
|
|
Senior Manager
Joined: 13 Jan 2012
Posts: 271
Weight: 170lbs
WE: Analyst (Other)
Followers: 4
Kudos [?]:
50
[0], given: 28
|
Re: When is the mean = median? [#permalink]
05 Jun 2012, 23:23
I've always thought of it like this, if you take the average of a group of evenly spaced numbers and that result is the middle number, then voila, mean = median.
For instance,
10, 20, 30, 50, 70, 80, 90
Mean = 50
Median = 50
Last edited by vandygrad11 on 27 Mar 2013, 12:45, edited 1 time in total.
|
|
|
|
|
|
Manager
Joined: 01 May 2012
Posts: 57
Location: Canada
GPA: 1
Followers: 2
Kudos [?]:
5
[0], given: 0
|
Re: When is the mean = median? [#permalink]
08 Jun 2012, 10:48
When there's no skew in the distribution.....
It's nice if you check out intro statistics (say, AP)
|
|
|
|
|
|
BSchool Forum Moderator
Status: Can't wait for August!
Joined: 13 Sep 2011
Posts: 877
Location: United States (MA)
Concentration: Marketing, Strategy
GMAT 1: 660 Q44 V37
GMAT 2: 680 Q45 V38
GMAT 3: 710 Q45 V42
GPA: 3.32
WE: Information Technology (Retail)
Followers: 13
Kudos [?]:
269
[0], given: 98
|
Re: When is the mean = median? [#permalink]
08 Jun 2012, 10:56
Simple explination,
Mean = median
When adding the diffence of every number from the mean in a set together = 0
example
(1,2,4,6,7)
Mean = 20/5 = 4
4-1=3
4-2=2
4-4=0
4-6=-2
4-7=-3
3+2+0-2-3=0
|
|
|
|
|
|
|
Re: When is the mean = median?
[#permalink]
08 Jun 2012, 10:56
|
|
|
|
|
|
|
|
|
|
|
close
