2013 AMC 8 第 7 题
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所有题目均经美国数学协会（MAA）官方合法授权使用。
7.
特雷和妈妈在铁路道口停下来让火车通过。火车刚开始通过时，特雷在前 秒数到 节车厢。火车以恒定速度完全通过道口用了 分 秒。下列哪一个最可能是这列火车的车厢数？
Trey and his mom stopped at a railroad crossing to let a train pass. As the train began to pass, Trey counted cars in the first seconds. It took the train minutes and seconds to clear the crossing at a constant speed. Which of the following was the most likely number of cars in the train?
小提示：
将总通过时间转换为秒
Convert the total crossing time to seconds.
大提示：
利用 秒通过 节车厢列出比例式
Use a proportion from cars in seconds.
视频讲解：
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文字解答：
分 秒等于 秒。因为 秒通过 节车厢，所以设 秒通过 节车厢，满足
解得 最接近的选项是 。
所以正确答案是 C。
Converting minutes and seconds into seconds, we get seconds. Since cars passed in seconds, at the same rate the number of cars passing in seconds satisfies
Solving gives The closest answer choice is .
Thus, C is the correct answer.
其他年份的第 7 题
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