1. Consider the tree diagram in the picture attached.
2 Each of the games picked can be a W (win) or a L (lose), the chances are equal
3. All that could happen in 4 picked games is shown in the picture:
2 w 2 l can happen in the following 6 ways: {(W,W,L,L)(W,L,W,L)(W,L,L,W)(L,W,W,L)(L,W,L,W)(L,L,W,W)}
4. P(2W,2L)=6/16=3/8
2 Each of the games picked can be a W (win) or a L (lose), the chances are equal
3. All that could happen in 4 picked games is shown in the picture:
2 w 2 l can happen in the following 6 ways: {(W,W,L,L)(W,L,W,L)(W,L,L,W)(L,W,W,L)(L,W,L,W)(L,L,W,W)}
4. P(2W,2L)=6/16=3/8