## Solution to CyberTeaser B238

Let V be the speed of the boat and v be the speed of the current. Then the distance between the boat and the raft grew at the rate (V + v) – v = V when the boat was going to B (here V + v is the velocity of the boat, taking the speed of the current into consideration). When the boat was going from B to A, the distance between it and the raft decreased at the same rate: (Vv) + v = V. So when they met, the time during which the distance between them increased was equal to the time during which it decreased: 1 hour.

Editor’s note: The physicists (or physics-inclined) among our readers got this one right away, it seems, seeing it as simply a frame-of-reference problem. One approach was to go to extremes (so to speak). “Obviously, the answer doesn’t depend on current speed,” wrote SConnery7, who preferred not to reveal his (her?) true identity. “Let it be 0. Answer: 1 hour.”

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