AMC10 2011 B

AMC10 2011 B · Q8

AMC10 2011 B · Q8. It mainly tests Logic puzzles.

At a certain beach if it is at least 80°F and sunny, then the beach will be crowded. On June 10 the beach was not crowded. What can be concluded about the weather conditions on June 10?

在某个海滩，如果温度至少 80°F 且晴天，则海滩会很拥挤。6 月 10 日海滩不拥挤。关于 6 月 10 日的天气条件可以得出什么结论？

(A) The temperature was cooler than 80°F and it was not sunny. 温度低于 80°F 且不晴天。

(B) The temperature was cooler than 80°F or it was not sunny. 温度低于 80°F 或不晴天。

(D) If the temperature was cooler than 80°F, then it was sunny. 如果温度低于 80°F，则晴天。

(E) If the temperature was cooler than 80°F, then it was not sunny. 如果温度低于 80°F，则不晴天。

Answer

Correct choice: (B)

正确答案：（B）

Solution

Answer (B): Because the beach was not crowded on June 10, at least one of the conditions was not met. That is, the weather might have been cooler than 80 °F and sunny, at least 80 °F and cloudy, or cooler than 80 °F and cloudy. The first possibility shows that (A) and (E) are invalid, the second shows that (C) is invalid, and the third shows that (D) is invalid. Only conclusion (B) is consistent with all three possibilities.

答案 (B)：因为 6 月 10 日海滩不拥挤，至少一个条件未满足。即可能是温度低于 80°F 但晴天、至少 80°F 但阴天，或温度低于 80°F 且阴天。第一种情况说明 (A) 和 (E) 无效，第二种说明 (C) 无效，第三种说明 (D) 无效。只有结论 (B) 与所有三种可能性一致。

Topics

LM.001 Logic puzzles