Am I understanding your question correctly?
Given 1830 minutes.
With the assumption that the average time to find a block is expected to be 10 minutes, it would be expected that 183 blocks would be found in this time.
You are asking what the chances are that exactly 60 blocks are found in that time, yielding an actual average of 30.5 minutes per block?
no. that would be impossible to calculate, cause you cant calculate who will buy how many new GPU's, who will deliver asic and when so no.
lets say i have 8.7Thash pool. its a perfect 8.7Thash , all the time no new users , no downtime, no ddos, perfect 0% stale 8.7Thash - shoud be 4575btc -183blocks in a week in current diff.
what is the chance to find 60 blocks in a week. what is a chance of being so ultra super unlucky - that is possible to calculate.
the 8.7T number is imaginary, just to be compatibile with my 183 blocks question.