Importance and expected number of harvested blocks calculation

Hi everyone,

I wanted to estimate a probability distribution for the number of blocks x harvested in a given time T given an importance of I for the symbol blockchain. If I’m not mistaken, that should be a binomial distribution with N = Number of blocks in T and p = probability of harvesting a single block.
x ~ Bin(N, p)

Now my question: How does the importance translate to the probability of harvesting a single block?

i) In the white paper it says “network:totalChainImportance equal to 9 billion”, but from my own calculations it’s more plausible that the total importance is 1.

ii) Is there a way to estimate the total importance that is actively harvesting. Because only that importance should be taken into account when I’m calculating the probability of finding a block.

Thank you very much in advance!