So, since I had a few keys to burn off today, I figured why not check to see what the drop rates are.
The random number of coins comes from the chest, as I discovered there are always 91 coins on the ramp and the types of coin there are random as well.
So if you are looking for something to figure how many runs you need to get where you want to be.
These numbers are pretty much what you will get.
I wish I did this sooner so it would have been more useful to more of you.