13.366. On a river with a current speed of 5 km/h, there are piers $A, B$, and $C$ in the direction of the current, with $B$ located halfway between $A$ and $C$. From pier $B$, a raft and a boat depart simultaneously in the direction of the current towards pier $C$, and the boat heads towards pier $A$, with the boat's speed in still water being $V$ km/h. Upon reaching pier $A$, the boat turns around and heads towards pier $C$. Find all values of $v$ for which the boat arrives at $C$ later than the raft.
Solution.

Let $x$ be half the distance between $A$ and $C$.

According to the condition $\frac{x}{V-5}+\frac{2 x}{V+5}>\frac{x}{2}$, from which $5<V<15$ (km/h).

Answer: $5<V<15$ km/h.