Numbers in mind puzzle
John has one of the numbers 1, 2, or 3 in mind. Jacob is allowed to ask one question to John to find out which of these three numbers he has in mind. John will answer this question only with the answers “yes”, “no”, or “I don’t know”.
Which question should Jacob ask John to find out in one time which number he has in mind?
I found a simpler answer than the one i gave above. Jacob will ask:
If you subtract 2 from your number, will the result be positive?
No means the chosen number is 1.
I don’t know the chosen number is 2 (since zero in neither positive nor negative)
Yes means the chosen number is 3.
Jacob will ask “Is the number in your mind greater than 2″?
If John says”Yes”, then it is obviously 3.
If he says”No”, then it is obviously 1.
If he says”I don’t know”, then it is 2 because, 2 is not greater than 2.
Similarly the question can be asked as ” Is the number in your mind less than 2″? and the same strategy be applied.
Answer for question “Is the number in your mind greater than 2″ NO means it can be 1 or 2 any of the number.
Jacob will ask: If I’ll draw a function of the degree of the number you have chosen will it have extremum?
A 1st degree function is a straight line so the answer is no.
A 2nd degree function has an extremum point so the answer is yes.
A 3rd degree function might have an extremum point but not always’ so the answer will be “I don’t know”
Your Answer
More puzzles to try-
What is the logic behind these ?
3 + 3 = 3 5 + 4 = 4 1 + 0 = 3 2 + 3 = 4 ...Read More »Defective stack of coins puzzle
There are 10 stacks of 10 coins each. Each coin weights 10 gms. However, one stack of coins is defective ...Read More »Which clock works best?
Which clock works best? The one that loses a minute a day or the one that doesn’t work at all?Read More »(Advanced) Cheryl’s Birthday Puzzle
Paul, Sam and Dean are assigned the task of figuring out two numbers. They get the following information: Both numbers ...Read More »Five greedy pirates and gold coin distribution Puzzle
Five puzzleFry ship’s pirates have obtained 100 gold coins and have to divide up the loot. The pirates are all ...Read More »Magical flowers!!
A devotee goes to three temples, temple1, temple2 and temple3 one after the other. In front of each temple, there ...Read More »Tuesday, Thursday what are other two days staring with T?
Four days are there which start with the letter ‘T‘. I can remember only two of them as “Tuesday , Thursday”. ...Read More »How could only 3 apples left
Two fathers took their sons to a fruit stall. Each man and son bought an apple, But when they returned ...Read More »How Many Eggs ?
A farmer is taking her eggs to the market in a cart, but she hits a pothole, which knocks over ...Read More »HARD MATHS – How much faster is one train from other Puzzle
Two trains starting at same time, one from Bangalore to Mysore and other in opposite direction arrive at their destination ...Read More »Most Analytical GOOGLE INTERVIEW Question Revealed
Let it be simple and as direct as possible. Interviewer : Tell me how much time (in days) and money would ...Read More »Lateral thinking sequence Puzzle
Solve this logic sequence puzzle by the correct digit- 8080 = 6 1357 = 0 2022 = 1 1999 = ...Read More »How did he know?
A man leaves his house in the morning to go to office and kisses his wife. In the evening on ...Read More »Pizza Cost Math Brain Teaser
Jasmine, Thibault, and Noah were having a night out and decided to order a pizza for $10. It turned out ...Read More »Which letter replaces the question mark
Which letter replaces the question markRead More »Which room is safest puzzle
A murderer is condemned to death. He has to choose between three rooms. The first is full of raging fires, ...Read More »Richie’s Number System
Richie established a very strange number system. According to her claim for different combination of 0 and 2 you will ...Read More »Srabon wanted to pass
The result of math class test came out. Fariha’s mark was an even number. Srabon got a prime!! Nabila got ...Read More »Become Normal!!
Robi is a very serious student. On the first day of this year his seriousness for study was 1 hour. ...Read More »Sakib Knows The Number!
Ragib: I got digits of a 2 digit number Sakib: Is it an odd? Ragib: Yes. Moreover, the sum of ...Read More »
