A column of cars 300 m long is driving on the highway at a speed of 60 km/h. Passing by a police checkpoint, each car reduces its speed to 40 km/h. What will be the length of the column when all cars have passed the checkpoint?

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For the time it takes for the last car to travel 300 m to the traffic police post, the first car will only travel $40 / 60 \cdot 300=200$ m from the post. This will be the new length of the convoy.

## Answer

$200 \mathrm{M}$.