Câu hỏi:
Two schoolgirls were traveling from the city to a dacha (summer cottage) on an electric train.
Đáp án:
If the girls had been on a standing train, the first girl's calculations would have been correct, but their train was moving. It took 5 minutes to meet a second train, but then it took the second train 5 more minutes to reach where the girls met the first train. So the time between trains is 10 minutes, not 5, and only 6 trains per hour arrive in the city.
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