That would be good. I have to do some extra work; that's not something hard but lot of works behind the scene. I guess I can do it without finding out the correlation between both the investment. Rather, I would put $100, $50 in BTC in $25 for each altcoin. It's the same thing, isn't it?
I'm not sure but putting $50 in BTC and $25 on each A and B means you're not well diversified. When Bitcoin goes down, A will go down too. You will have loss on two coins (BTC and A) and positive on one (B). You should only put BTC and B or A and B if you're looking to diversify your portfolio and minimize your risk.I actually do not trust this "predictor" site to give out correlations without knowing the algorithm behind it. Do you have any idea what algorithm they might be using? Unless I know that I wont use it. Also if I know that then I would probably learn how to apply it myself. 
The algorithm is simple. As I said above, they just have had some math on the last 100 days & based on that, they have calculated the correlation.
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You can even do it yourself using Excel (=CORREL) if you have the historical price data, which you can get from sites like CryptoCompare for free.