Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2013-07-30 13:52:19

tina123
Member
Registered: 2012-04-29
Posts: 83

meaning of mean, mean as cluster, mean as centriod

What does mean by mean?
What is the actual meaning of mean?
Let say you have 10 points like this

9, 5 , 8,10,8,7,11,8,4,6,9,11,4

Where would be the mean?

another example

9, 5 , 8,10,8,7,11,8,4,178,9,11,20

Kindly, tell where would be the mean?

Can we say that mean value represents the all number of values?
or we will say that mean is the average of the nearest number?

like in this example
9, 5 , 8,10,8,7,11,8,4,6,9,11,4
mean would near to these values
like in this example,.
9, 5 , 8,10,8,7,11,8,4,178,9,11,20
mean would be near the values but would not go to the so different values with others . like 20 and 178..i meant outlair.

Can we say that mean represent the cluster?

Can we say that mean represent the cluster?

Mean is also called centro-id of points. Right ,

Offline

#2 2013-07-30 18:07:57

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,885

Re: meaning of mean, mean as cluster, mean as centriod

Hi tina123;

The mean of the first one is 100 / 13.

The second group of data has a mean of 288 / 13.

The mean is just the average of all the numbers.


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

Offline

#3 2013-07-30 20:10:57

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,538

Re: meaning of mean, mean as cluster, mean as centriod

hi tina123

The diagram below shows one way to think about the mean.

Bob

View Image: tina123c.gif

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

Offline

#4 2013-07-30 20:36:30

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,538

Re: meaning of mean, mean as cluster, mean as centriod

and this diagram shows a centroid G

There is a weightless beam pivoted at one end, A.

There are three weights on the beam;  4 Kg at a distance 2 units from A, 3 Kg at a distance 4 units from A, and 3 Kg at a distance 6 units from A.

The total weight is 10 Kg.

The centroid is the point on the beam at which 10 Kg would give the same turning moment.

(note: turning moment is weight x distance )

moments about A:  4 x 2 + 3 x 4 + 3 x 6 = 8 + 12 + 18 = 38.

OR : total x AG => AG = 38/10 = 3.8

Bob

ps.  Don't know what to do for 'cluster'.  smile

View Image: tina123d.gif

You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

Offline

Board footer

Powered by FluxBB