(1) At first, the spots are 1,2,3,4,5,6. After the change, the spots are 1,3,3,5,5,6.

P(even number)=...

(2)(a) Perhaps it will help by drawing a tree diagram. This is an example of a conditional probability.

Let R be the event of the first cube drawn is red and Q the event of drawing at least 2 red cubes.

P(Q n R)=P(RRB)+P(RBR)+P(RRR)

P(R)=P(RRR)+P(RRB)+P(RBR)+P(RBB)

P(Q|R)=P(R n Q)/P(R)

(b) You can do the same here but this time its drawing without replacement.