15. (12 points) The NBA Finals are between the Los Angeles Lakers and the Boston Celtics, with the series being a best-of-seven, meaning the first team to win 4 games will be the champion. The games are divided into home and away matches. Due to the Los Angeles Lakers' better regular-season record, the 1st, 2nd, 6th, and 7th games are played in Los Angeles, while the 3rd to 5th games are played in Boston. The Lakers ultimately win the championship on their home court. How many possible outcomes are there for the series? $\qquad$ kinds.
【Solution】Solution: To win the championship, one must win four of the games, and the games played at the Lakers' home court are the 1st, 2nd, 6th, and 7th games. To win the championship at home, it can only happen in the 6th or 7th game. We will discuss this in two scenarios:
(1) The Lakers win the championship in the 6th game, so the score in the first five games should be $3: 2$. Out of the 5 games, any 3 can be chosen to win, and the rest to lose, which gives us the possible scenarios:
$$
\frac{5!}{3! \times 2!}=\frac{5 \times 4 \times 3 \times 2 \times 1}{3 \times 2 \times 1 \times 2 \times 1}=10 \text { (ways). }
$$
(2) The Lakers win the championship in the 7th game, so the score in the first six games should be 3:3. Out of the 6 games, any 3 can be chosen to win, which gives us the possible scenarios:
$$
\frac{6!}{3! \times 3!}=\frac{6 \times 5 \times 4 \times 3 \times 2 \times 1}{3 \times 2 \times 1 \times 3 \times 2 \times 1}=20(\text { ways })
$$

In summary, there are $10+20=30$ possible scenarios.
Answer: There are 30 possible outcomes for the win-loss results in the series.
Therefore, the answer is: 30.