Answer:
5 or less
Step-by-step explanation:
The speed increased linearly with distance, but is not decreasing linearly with distance. This suggests the track has an unknown shape, so prediction of car behavior is a guess, at best.
If the car continues to decrease its speed at 3 units per unit distance, then the final 3 units of speed will decrease to 0 in one additional unit of distance. That is, the car will stop at a distance of 5 units.
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Since the car has be decreasing its speed at an increasing rate with respect to distance, very possibly the car will stop before it reaches distance unit 5.
Since we don't know the track shape, it seems possible the car may not stop until some large unknown number of distance units, say 10 or 1000.
