Extra Exercise 3
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(a) False.
There is on the average 4 nines among 40 random digits, but the number
of nines among a specific set of 40 random digits is random.

(b) True.
There are exactly 100 two-digit numbers, and they all have the same
probability - which therefore is 1/100.

(c) False.
9999 is equally random as all other 4-digits numbers, if generated from
random digits. It therefore can appear as a group, but it actually does not
seem to appear in Table A. The table contains 40*50=2000 digits, which
is too small for a particular 4-digit sequence to appear with high
probability. There are however many patterns consisting of the same digit
three times in succession (such patterns are much more likely to occur), 
try to spot some of them in the table.