8. Car A and Car B start from locations $A$ and $B$ respectively at the same time, heading towards each other. They meet after 3 hours, then Car A 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 half an hour later. How many minutes does it take for Car B to travel from $A$ to B?
Analysis: As shown in the figure, assume the first meeting point is location $\mathrm{C}$, and the second meeting point is location D. Car A took 3 hours to reach point $\mathrm{C}$, so it must have taken another 3 hours to return to point $\mathrm{A}$. From $\mathrm{A}$ to D, Car A used half an hour. According to the constant speed, the distance ratio equals the time ratio, $\mathrm{AC}=6 \mathrm{AD}, \mathrm{CD}=5 \mathrm{AD}$. Given that Car B took 3.5 hours to complete CD, therefore, Car B should spend $3.5 \div 5=0.7$ (hours) to travel AD. Therefore, Car B needs a total of 3+3.5+0.7=7.2 (hours) to travel from A to B, which is 432 minutes.