Weighted Average or Weighted Mean

First and foremost, what is the need of this weighted stuff.

Let us understand this through an example:-
Lets say you want to go for a movie but you want to be sure that its a good movie. So you visit different movie-review websites and note the score for the movie.
(The score is out of 5)
Let the scores be :-

Site 1: 4
Site 2 : 2
Site 3: 3
Site 4: 2
Site 5: 2

Next you take the average to get the average rating of the movie.

But, you know, that Site 1 is a more popular others. So you want to take that into account in your calculations as well.

So, this is where the concept of weighted mean comes into practice:-

You assign the weight 2 to Site 1 and 1 to others.

The Weighted Average Reading for the movie will be


Weighted Average Rating = (4*2 + 2*1+ 3*1 + 2*1 + 2*1) / (2+1+1+1+1) = 2.82


Looking at the above calculation I am inclined to say that the normal average is a special case of weighted average, where the weights for all the reading is same and is equal to 1.

Average Rating = (4*1 + 2*1+ 3*1 + 2*1 + 2*1) / (1+1+1+1+1) = 2.6


As we can see, the weighted average is more than the normal average as we gave higher weightage to a site which give more marks to movie than others (or more than the normal average to be precise :)).


Lets see one more example:-

Suppose there are 20 kg of rice1 costing 50\kg and there is another variety of rice, say rice2 costing 60\ kg.

Suppose we mix
rice1 = 5 kg
and
rice2 = 6 kg

what will be the per kg cost of the mixture.

Here:-

Per Kg Cost of the Mixture = (Total Cost) / Total weight

(250+360) / 11 = 610/11

Life or Something like that

http://www.marcandangel.com/2011/12/11/30-things-to-stop-doing-to-yourself/

Kindly Visit for an Eye Opener Session,
Ashish Mishra

Closed Figures

Closed Figure: A figure that can be traced with the same starting and stopping points, and without crossing or retracing any part of the figure. Any polygon is an example of a closed figure.