Weighted Average

[Explain this!]

The index i represents the subscripts; it ranges from 1 to 3. This is not the same as the values of the quantities.

Have you read about sigma notation, in order to understand what it means? Try here:

Sigma Notation

Yes, I have checked online. I assume that the upper index would be "n" if the number of subscripts is unknown or not determined.

 

[Deleted member 4993]

I'm not sure what you are referring to. There is no weight of 3.

You are misinterpreting the term "weight" here!

In your original problem, it is said:

..............Type C: 4 boxes @ $0.42

That translates to -

the 3rd. bunch (C) - which is designated W₃ has 4 boxes \(\displaystyle \ \to \

\) W₃ = 4

 

[Explain this!]

Yes, I understand W₃ is the weight of 4 boxes and $0.42 is the value X₃. This is as you indicated 4 boxes @ $0.42.
But what is i = 3 in you answer: "... your problem, W3 = 4, and i = 3." Are you referring to the total number of subscripts, 3 of them?

 

[Dr.Peterson]

Yes, I have checked online. I assume that the upper index would be "n" if the number of subscripts is unknown or not determined.

Yes, n would be replaced with whatever the highest index is, when you apply such a formula. So the number on top is that highest index. If the summation starts at "i=1", that will be the number of terms; but it could start at 0, or anything else. Meanwhile, i is the index of any particular term. (See the last example in the page I referred you to, for one that starts at i=3.