What is the sum of the products of price times quantity divided by sum of quantities I have a very simple question, what is the meaning, if any, of this?
I.e. mathematically what does the following calculation mean?
$$
\left(\frac{(Q1\cdot P1)+(Q2\cdot P2)+(Q3\cdot P3)}{Q1 + Q2 + Q3}\right)
$$
Can think of the values being in a table like the one shown below?
$$
\begin{array}{c|lcr}
n & \text{Factory A Generation of good x} & \text{Factory B Generation of good x} & \text{Market price for good x} \\
\hline
1 & Q1 & Q1 & P1 \\
2 & Q2 & Q2 & P2 \\
3 & Q3 & Q3 & P3 
\end{array}
$$
Thank you!
 A: Let us say you have a product $x$ and there is one company with three different branches $A$, $B$ and $C$ producing the quantities $Q1$ , $Q2$ and $Q3$ respectively. These companies are located in different areas. Any product can be produced depending on the availability of resources, human resource as well as the capital which means every branch while producing the product will incur a different manufacturing charge. Now each of the branches can sell this product at different prices depending on the profit they want to earn.
Let us say the selling price of the product $x$ is $P1$, $P2$, and $P3$ respectively as charged by the branches $Q1$, $Q2$ and $Q3$ .
The total price of the product $x$ will be : 
$$Q1.P1+Q2.P2+Q3.P3$$
which will be different for each branch of the company. You can consider this quantity as the total profit that has been earned by the company from its three branches.
Now the company wants to see which branch A,B or C has performed well in earning profits so the company can compare $Q1.P1,\space Q2.P2,\space Q3.P3$ obviously each branch performs differently.
Finally the company would like to check what has been the average profit of the product $x$ so it will use the quantity $$\frac{Q1.P1+Q2.P2+Q3.P3}{Q1+Q2+Q3}$$
because not all the branches are having the same profits so the company would average it out. Averaging usually balances out the lower and higher profits so that we can say that on average this profit is earned by the company.
\begin{array}{|c|}
\hline
 & \text{Quantity (Units) } & \text{Price (USD)} & \text{Market price }& \\
\hline
 \text{Factory A } & Q1 & P1 & Q1.P1 \\
 \text{Factory B } & Q2 & P2 & Q2.P2 \\
 \text{Factory C } & Q3 & P3 & Q3.P3 \\
\hline
 \text{Total} & Q1+Q2+ Q3& P1+P2+P3 & Q1.P1+Q2.P2+Q3.P3\\
\hline
 \end{array}
Hope this helps ......
