Can weighted average be used to calculate percentage increase? [duplicate]

Possible Duplicate:
Is this a weighted average/percentage problem?

Let's say a Marketing company has a total turnover of 10000 \$There are 3 salesmen A,B,C with the following turnovers: The turnovers have two components - Income and Expenses: A = 2000$
B = 3000 $C = 5000$
Ia = 80% = 1600 $Ib = 70% = 2100$
Ic = 60% = 3000 $Ea = 20% = 400$
Eb = 30% = 900 $Ec = 40% = 2000$
Total Income = 6700 USD = 67%
Total Expense = 3300 USD = 33%


Now, If the company wants to increase total Income by 10 %, How should this increase be split across the Incomes of A,B,C? Is this a weighted average/percentage increase problem?

-

marked as duplicate by Raskolnikov, Did, leonbloy, Arturo Magidin, mixedmath♦Jul 19 '11 at 17:11

Whoa - not cool. This is your other question, with a tidbit added at the end. –  mixedmath Jul 19 '11 at 17:03
I was not sure if weighted average method can be applied to both subtotals and deltas in subtotals. I have rephrased my question now –  Sathish Jul 19 '11 at 17:12
This question has been closed. You should edit and change your other question (the copy of this one) to reflect your question. –  mixedmath Jul 19 '11 at 17:13
Also note that you can pick up a copy of the whole post and move it over, if absolutely necessary. Or the post history by clicking on the time (e.g. edited 3 mins ago). –  mixedmath Jul 19 '11 at 17:14

In this case, you want $0.8 A_+ + 0.7 B_+ + 0.6 C_+ = 670$. Here, I use letter$_+$ to indicate the additional turnover to the person with that letter. In a sense, that's a weighted average problem... but that's not how I would solve it (I would do it as above).
@Sathish: yes - but that is not increasing the income by 10%. Now you have a weighted average. You are solving $\dfrac{6700 + D}{10000 + D} = 0.77$. This has a solution - but I'll let you find it. –  mixedmath Jul 19 '11 at 19:35