SOLUTION: I would like to know the total % gains of an investment fund that contains 4 different items that all amount to a different percentage of the investment. i.e Gold is 20% of the i

Question 717059: I would like to know the total % gains of an investment fund that contains 4 different items that all amount to a different percentage of the investment.
i.e
Gold is 20% of the investment and has gained 4.2%
Silver is 20% of the investment and has gained 6.1%
Platinum is 30% of the investment and has gained 10.7%
Palladium is 30% of the investment and has gained 25.2%
I know that to get the average gain of the fund i simply add the 4 % gains and divide by 4 (giving 11.6%)
But I wish to know the amount of percentage that the fund has gained in total.
Answer by KMST(5328) (Show Source): You can put this solution on YOUR website!
20% of anything means 20 out of every 100, so it is calculated by multiplying times the ratio or decimal

4.2% of anything means 4.2 out of every 100, so it is calculated by multiplying times the ratio or decimal

As a fraction of the total invested, the gain from just the 20% of the total amount that has gained 4.2% can be calculated as many expressions:
or 0.84%
It seems to me that the easiest way to calculate it and understand it is
%
Since investments often are apportioned as 10% or 20% or 30% of the total amount invested (all multiples of 10%), you end up just multiplying each percent gain times an easy decimal, like 0.1, or 0.2, or 0.3.
Adding all the gains as a fraction of the total invested we get the total gain as a fraction of the total invested:
%
I would call that the average gain.
It can be called a weighted average because in this calculation you give each individual investment the correct weight based on what fraction of the total investment it represents.
It is the number that matters.
An average calculated from adding all the individual % gains and dividing by the number of different investments gives all those different investments the same weight, as if each ones represented of the total invested.
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