11. Xiao Ming rides a bike, and Xiao Ming's father walks. They start from $A$ and $B$ respectively and move towards each other. After they meet, Xiao Ming takes another 18 minutes to reach $B$. It is known that Xiao Ming's cycling speed is 4 times his father's walking speed. Xiao Ming's father needs another  minutes to walk from the meeting point to $A$.
【Answer】288 minutes
【Key Point】Travel Problem
As shown in the figure, when Xiao Ming meets his father, since Xiao Ming's speed is 4 times that of his father and both have been moving for the same amount of time, Xiao Ming's distance should be 4 times that of his father (the $4 S$ and $S$ in the figure);
After meeting, Xiao Ming takes another 18 minutes to travel the distance $S$ to reach point $B$; since Xiao Ming's speed is 4 times that of his father, it would take his father $18 \times 4=72$ minutes to walk the distance $S$; since his father still needs to walk another $4 S$ from the meeting point to point $A$, it would take Xiao Ming's father another $72 \times 4=288$ minutes to walk from the meeting point to point $A$.