Question 25. The inhabitants of a certain city always speak by means of questions. There are two types of inhabitants, the positives, who always ask questions for which the answer is yes, and the negatives, who always ask questions for which the answer is no. I met Albert and Berta. Berta asked me whether Albert and I are both negative. What type of inhabitants are Albert and Berta? Let's start off with assuming that they're positives, both of them. Are Albert and I both negative? If they were positives, then Berta would be asking a question with the answer of yes. If they were both negative, then they can't also be positives. So the answer, if yes, means that they are both negative. So they cannot be both positives since they would have to ask a question that has the answer of yes, but they are asking that they are negative. So it is not A. Next, since Berta asked the question, are Albert and I both negative? We know that Berta must be negative since we concluded that they are both not positives. So Albert is a negative and Berta is a positive is not an answer. We know that one of them is a positive and one of them is a negative. So the answer will be C. Albert is a positive. Berta is a negative.

positives

negatives

Albert

Berta

questions