Question 17
Trọng drives a motorboat upstream from $A$ towards $C$. The boat’s speed is 22 km/h. At $D$ he drops a life jacket, but notices only on reaching $C$, immediately turns back, and retrieves it at $B$. Exactly 1 hour elapses between dropping and retrieving the jacket. The current flows at 2 km/h. Find $BD/CD$.
Model clarification: 22 km/h is the boat’s speed in still water; the jacket drifts with the current and the boat maintains that speed relative to the water.
Model clarification: 22 km/h is the boat’s speed in still water; the jacket drifts with the current and the boat maintains that speed relative to the water.