I'd like to get the global average of 2 numbers in their proportions. How's that possible?
Here is the example of what I want:
a = 3084
a1 = 0.35
b = 2349
b1 = 0.52
I want to get a1 + b1's average based on the ratios we get by:
a + b = 5433
a_percent = 0.567
b_percent = 0.433
So I want to get the average of a1 & b1 based on the ratio of 0.567 : 0.433
If I simply get the average of a1 + b1 then it's going to be 0.435 but it's not calculating the ratios.
Sorry if my description is so basic, I haven't learned anything like this before, so I don't know how to express myself. Just let me know if you need anything else.
Best Answer
What you want is called a weighted average, and you have calculated the important parts already, what you call "a_percent" and "b_percent". The formula you are looking for is
$$\text{average}_\text{weighted} =\text{a_percent}\times a_1 + \text{b_percent}\times b_1$$ $$\text{average}_\text{weighted} =0.567\times 0.35 + 0.433\times 0.52 \approx 0.42.$$
Since the relative weights ($0.567$ and $0.433$) are near $0.5$, the weighted average is near the 'normal' average ($\frac{a_1+b_1}2 = 0.5\times a_1 + 0.5 \times b_1 = 0.435$).
Since the weight for $a_1$ is bigger than $0.5$, one would presume that the weigthed average is slightly nearer to $a_1$ than the normal average, which is correct.