1/2
1/6
2. Not necessarily, the probability is random.
3. Let the length of bamboo pole be x meters and the distance between AB be 10-x meters, so 10-x=0.25x, so x=8.
4. The van * * * walked 3/4+3/5=27/20, and when they met, they walked 7/20 of the whole journey, which is 84 kilometers. So the whole journey is 84/(7/20)=240 km.