podiel súčtu

15:15 Mar 3, 2013 

Well, so it's pretty simple then. Just show where my thinking is wrong in the below example and what you mean by a "weighted average" here. For the sake of simplicity and uniform approach, please use the five daily values given in the example.
Thank you.

15:04 Mar 3, 2013 

With all due respect, that's just plain wrong.

I will post no more on this question :-)

15:04 Mar 3, 2013 

úplne presne!

15:01 Mar 3, 2013 

Let me give you an example. Say the daily prices are as follows:

Mo: €1.25
Tue: €1.27
We: €1.25
Thu: €1.26
Fri: €1.24

The arithmetic average would be calculated as follows: (1.25+1.27+1.25+1.26+1.24)/5 = €1.254

There is no "weighted average" as all the daily values have a weight of 1.

But assume, you want to take into account the volume of gas sold on each day. On Mo, you sell 1500 l, on Tue 1300 l, on Wed 1000 l, on Thu 1100 l, Fri 2000 l.

Then you can calculate the weighted avg price as follows: (1500*1.25+1300*1.27+1000*1.25+1100*1.26+2000*1.24)/(1500+1300+1000+1100+2000)*5 = €1.2524

So, the weighted 5-day average price taking into account the volume sold on each day would be €1.2524. The daily prices are weigted as per the volume sold.

14:39 Mar 3, 2013 

There isn't enough context to make clear what operation is being carried out here! I'm reading "jedného litra" as "per litre" rather than "one litre" (because one litre seems meaningless to me).

Weighting by day number would be weird!

14:12 Mar 3, 2013 

I think that what DLyons says is a common misunderstanding of the concept of a weighted average. In this situation, the "weighted" average equals arithmetic average, so there is no need to call this average "weighted". A weighed average would make sense if, for instance, the price on a certain day would be more/less important than the other ones and would, therefore, be given a special "weight"

14:09 Mar 3, 2013 

in the question is specified: "one liter". There are no other units.

13:59 Mar 3, 2013 

Weighting would normally be done by the number of units of each type.

13:55 Mar 3, 2013 

by to bol, ak by sa niektorým hodnotám prikladala rôzna "váha". Napr. posledný deň/týždeň by mal váhu "4", predposledný "3", atď.

13:41 Mar 3, 2013 

cena je vypocitana ako podiel suctu dennych/tyzdennych hodnot a poctu jednotlivych cien

13:35 Mar 3, 2013 

yes, average price

13:06 Mar 3, 2013 

is this supposed to be a calculation of an average price?