I wonder that the odds are for a 90min block?
imagine we get really unlucky and hit a 3 year block
Assuming a constant hashrate:
-The probability that a block won't be found after 10 minutes is 50%, or .5.
-The probability that a block won't be found after 20 minutes is .5 * .5 = .5 ^ 2 = 25%.
-The probability that a block won't be found after 90 minutes is .00195, 0.2%, indicating 1-in-512 blocks can be expected to take 90 minutes or more (averaging about one in four days with long-term sampling)
-The probability that a block won't be found after one day of mining is .5 ^ 144 = 0.000000000000000000000000000000000000000005%