Question 1120139

a)  (1/10)*(1/10)*(1/10) = {{{ highlight ( 1/1000 ) }}}  = 0.001
b)  (1/10)*(1/10) =  {{{ highlight ( 1/100 ) }}}  = 0.01

Notice for part(b) that the first pick is x (where x=0,1,…9), so only the 2nd and 3rd picks need to match x. In contrast, part(a) stipulates that x=2 so we have a 1/10 probability of picking that particular x on pick #1.   
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An alternate way to view (b) vs (a):  there are 10 possible picks where the 3 numbers match, and only one {2,2,2}, so the answer to (b) must be 10 times as great as (a).