[填空题]
A lego storage box is left with 4 blue and 7 red bricbrbxd9kdv +,vn4*d/6 h c q-ouks. Max t:)b io2ru1 w 9sfuxz,wj. h0 chf8r4cpakes a brick from the box at random and attacheswx,01fjuhw4zhf.pb c2 s r)u89ir:oc it to his new castle. He then chooses another brick fron the same box at random.
1.Complete the following tree diagram.
2.Calculate the probability that both bricks chosen by Max are of the same color.≈