8. (10 points) Cars A and B start from locations $A$ and $B$ respectively at the same time, heading towards each other. They meet after 3 hours. Car A then turns around and heads back to $A$, while Car B continues on. After Car A reaches $A$ and turns around to head towards $B$, it meets Car B again after half an hour. How long does it take for Car B to travel from $A$ to $B$? $\qquad$ hours.
【Analysis】After meeting, A still needs 3 hours to return to A's place. At the second meeting, the distance A is from the meeting point is equal to the distance A can travel in 2.5 hours. B takes 3.5 hours to travel this distance, so the speed ratio of A to B is 7:5. A and B meet after 3 hours, so B alone would need $3 \times 12 \div 5=7.2$ hours.

【Solution】Solution: $(3+0.5):(3-0.5)=7: 5$,
$$
\begin{array}{l}
3 \times(7+5) \div 5 \\
=7.2 \text { (hours) }
\end{array}
$$

Answer: B needs 7.2 hours to travel from A to B.
The answer is: 7.2.