Question 1168716
These are independent probability of each is (1/6), probability of both is 1/36. Also, what happens on first roll has no bearing upon the second roll.


The second isn't clear.  If a is one roll and b is a different roll with BOTH die, then they are independent. 
If, however, a is the first roll, then b is a roll of the other die, and the two are added, then this is a dependent case, since the roll in the first case has direct bearing upon the sum in the second case.  If it is a 3, then the second die need to be 4,5,6.  If the first were a 1, then the second would have to be a 6.

(1/6)(1/2)=(1/3), since the second die has to be 4,5,6.
separately, they are (1/6) and (21/36) or (7/12), and that product is 7/72.