AMC 8 2020 Problem 6
AMC8 2020 年第 6 题
逻辑推理（跨域）★★☆☆☆
Aaron, Darren, Karen, Maren, and Sharon rode on a small train that has five cars that seat one person each. Maren sat in the last car. Aaron sat directly behind Sharon. Darren sat in one of the cars in front of Aaron. At least one person sat between Karen and Darren. Who sat in the middle car?
Aaron，Darren，Karen，Maren 和 Sharon 乘坐一列小火车，火车有五节车厢，每节车厢可坐一人。Maren 坐在最后一节车厢里。Aaron 坐在 Sharon 的正后方。Darren 坐在 Aaron 前面的某节车厢里。至少有一个人坐在 Karen 和 Darren 之间。谁坐在中间的那节车厢里？
- A.
- B.
- C.
- D.
- E.
正确答案 · Correct Answer
A
解析 · Solution
Solution 1
Write the order of the cars as , where the left end of the row represents the back of the train and the right end represents the front. Call the people , , , , and respectively. The first condition gives , so we try , , and . In the first case, as sat in front of , we must have or , which do not comply with the last condition. In the second case, we obtain , which works, while the third case is obviously impossible since it results in there being no way for to sit in front of . It follows that, with the only possible arrangement being , the person sitting in the middle car is .
Follow the first few steps of. We must have , and also have . There are only 4 spaces available for A, S, D, K, so the only possible arrangement of them is , so the arrangement is , so the person in the middle car is .
继续练习