Not a mathematician, but I'm sure the probability of them all being below 384 is going to be in the order of 0.000000001% if not less :)
10 times the amount of digits is the possible number space.
smaller than 384 means 384 numbers (including 0) divided by the amount of possible numbers (see above) imho
Sure, if they were actually sampling 384 bits. Sounds like they sampled a lot less than that; maybe someone though "384 bits" meant "in the range [0, 383]" or whatever.