Ask for a logical reasoning question for the master to save his life

I have a similar one

1.Xiao Ming and Xiao Qiang are both students of Teacher Zhang, and Teacher Zhang's birthday is the nth day of the month of M, and neither of them knows. Mr. Zhang's birthday is one of the following 10 groups, Mr. Zhang told Xiao Ming the m value and Xiao Qiang the n value, and Mr. Zhang asked them if they knew what his birthday was.

March 4, March 5, March 8.

June 4 June 7.

September 1 September 5.

December 1, December 2, December 8.

Xiao Ming said: If I don't know, Xiao Qiang definitely doesn't know.

Xiaoqiang said: I didn't know it at first, but now I know.

Xiao Ming said: Oh, then I know too.

Please deduce from the above conversation what is Mr. Zhang's birthday?

Analysis: From 10 sets of data: March 4, March 5, March 8, June 4, June 7, September 1, September 5, December 1, December 2, December 8, it can be seen that there were two groups on the 4th, 8th, 5th, and 1st, and only one group on the 2nd and 7th. If your birthday is June 7 or December 2, Xiaoqiang must know (for example:

The teacher told Xiaoqiang n 7, then Xiaoqiang knew that his birthday must be June 7; If the teacher tells Qiang n 4, will the birthday be March 4 or June 4? Xiaoqiang can't be sure).

1、."Xiao Ming said: If I don't know, Xiao Qiang definitely doesn't know" The teacher told Xiao Ming that the month m value, if m 6 or 12, then Xiao Qiang may know (June 7 or December 2) This contradicts "Xiao Qiang definitely doesn't know", so it can't be June and December.

Therefore, the teacher's birthday can only be March 4th, March 5th, March 8th, January 1st, and September 5th.

2. "Xiaoqiang said: I didn't know it at first, but now I know" If the teacher tells Xiaoqiang n 5, then Xiaoqiang can't know if it's March 5 or September 5? This contradicts "now I know", so n is not equal to 5.

Birthdays can only be on March 4th, March 8th, and September 1st.

3. "Xiao Ming said: Oh, then I know too!" If the teacher tells Ming M 3, he doesn't know if it's March 4 or March 8. This contradicts "then I know too". So m is not equal to 3, i.e. the birthday is not March 4, March 8.

To sum up: Mr. Zhang's birthday can only be September 1.

Two cards must be flipped over: the first and fourth.

1. Turn over the first one and see if there is a triangle on the back.

2. Turn over the fourth one to see if the back is black.

The other two, one is not black, and the other is not triangular, so you don't need to turn it over.

Categories: Entertainment & Leisure >> brain teasers.

Problem description: 1. Hat problem.

There was a Turkish businessman who wanted to find an assistant to assist him in his business. But the assistant he wanted had to be very smart. Three days after the news broke, two people, A and B, came to contact.

The merchant, in order to see which of the two men A and B was smarter, led them into a dark house where he could not see his fingers. The merchant turned on the light and said"There are five hats on this table, two in red and three in black.

Now, I turned off the lights and messed up the position of the hats, and then each of the three of us touched a hat and put it on our heads. When I turn on the lights, please tell me as soon as possible what color hat you are wearing on your head. "After saying this, the merchant turned off the electric light, and then all three men touched a hat and put it on their heads; At the same time, the merchant hid the remaining two hats.

When all this was done, the merchant turned the lights back on. At this time, the two men saw that the merchant was wearing a red hat on his head.

After a while, A shouted:"I'm wearing a black hat. "How is A reasoned?

Analysis: If A is red, B can immediately judge that he is black, but B doesn't guess, then A's hat must be black!