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Professor Riddle

Professor Riddle - 4 july

A professor thinks of two consecutive numbers between 1 and 10.
'A' knows the 1st number and 'B' knows the second number

A: I do not know your number.
B: Neither do I know your number.
A: Now I know.

There are four solution for this.What are they ??


For Solution: Click Here

32 comments:

  1. 2,3 and 8,9 are possible ansswers.

    ReplyDelete
    Replies
    1. 2+5+7=141711
      4+8+1=133344
      6+2+4=121614
      3+5+4=121917

      2+6+8=??????

      Delete
    2. Wats al this shit about?????? Its either...
      1,2 or 9,10 easy

      Delete
  2. Replies
    1. It cannot be (2,3) because if person A has number 2, person B cannot have number 1, so person A knows that B would have 3. If person A has number 3, and person B has number 3, person B would know.

      Delete
  3. 7,8
    8,7
    3,4
    4,3

    ReplyDelete
  4. NKG, the Answer is

    ist sol= 2-3
    2nd Sol= 4-5
    3rd Sol= 6-7
    4th Sol= 8-9

    ReplyDelete
    Replies
    1. 2+5+7=141711
      4+8+1=133344
      6+2+4=121614
      3+5+4=121917

      2+6+8=??????

      Delete
  5. plz exlain me the solution of this

    ReplyDelete
  6. If A or B had 1 or 10, then they would have solved it straight away. But neither did.

    But when B discovered that A didn't know, he went from not knowing to knowing. So B must have had a number where A's answer was crucial.

    If B had 2, then A could have 1 or 3 - and the crucial answer "I don't know your number, either" would have ruled out 1, leaving 3 as the other number (Solution: 2 and 3)

    Now, if B had 3, then he would expect A to have either 2 or 4. But if A had 2, A could have guessed the answer already (because B had already said he didn't know, so could not have had 1). When B discovers that A also doesn't know, he can rule out 2 as the answer. (Solution: 3 and 4).

    Exactly the same arguments work at the other end of the range, providing the other two solutions: (Solution: 9 and 8) and (Solution: 8 and 7)

    ReplyDelete
    Replies
    1. 2+5+7=141711
      4+8+1=133344
      6+2+4=121614
      3+5+4=121917

      2+6+8=??????

      Delete
    2. Only two possible solutions: [3,4] and [7,8].

      A does not know, thus he has a number [2,9] (at this stage).
      B does not know either. This means he has a number from [3,8] and by extension A has a number [4,7]. If A had 2, and B had 1, B would have known A's number, but since they both don't know, B must either have the number 3 or 7 to open the possibility of A having 4 or 8.
      Since A now knows, it excludes the possibility of [4,5] and [6,7], leaving [3,4] and [7,8].

      Delete
    3. The Answer is only A-2,B-3 and A-9,B-8. I could not understand your explanation.
      "But if A had 2, A could have guessed the answer already" - contradictory statement! since 2,3 is an answer!!!!

      Delete
    4. the answers are:
      a=2 b=3
      a's answer cannot be 1 or 10 because otherwise he would know that b was 2. the fact that b doesn't know either means b isn't 1 or 10 either. As a is 2, b's only possible solutions are 1 and 3, and as we know b can't be 1, a would now know that b is 3.
      a=9 b=8
      Same as before, a is 9 and doesn't know whether b is 10 or 8. But as b doesn't know either, it can't be 10, therefore it is 8
      a=8 b=7
      Now this and the next one are a lot more difficult to solve; you need to see the crucial thing between a and b; a originally tells b that it doesn't know b's number, and with this knowledge b still is unable to work out a's number. However, a is able to work out b's number with the knowledge that b doesn't know its number. When a is 4, 5, 6, or 7 there is no possible way for a to know b's number without more information. However, with 8 we can use the solution we had for the first two answers to prove that b cannot be 9; if it were it would be able to work out what a was when a originally told b that it didn't know its number. So the fact that telling b that a didn't know b's number didn't make b know a's number meant that b must 7.
      a=3 b=4
      Same solution as the previous one, but using the fact that b would work out that a was 3 if b was 2, meaning it has to be 4.

      Delete
    5. But it said "between 1 and 10"...surely that does not include 1 and 10 as possibilities?

      Delete
    6. Gaping flaw in this logic: "Now, if B had 3, then he would expect A to have either 2 or 4. But if A had 2, A could have guessed the answer already (because B had already said he didn't know, so could not have had 1). When B discovers that A also doesn't know, he can rule out 2 as the answer. (Solution: 3 and 4)."

      Description in the riddle only states that A knows the answer, not B. This whole (4,3) and (8,7) answer relies on the fact that B's number MUST be sequentially follow A's number which the logic to the valid answers (2,3) and (8,9) proves is not the case. Additionally the riddle never states this. The only four valid answers are (A,B) = (2,3),(3,2),(8,9),(9,8).

      Delete
    7. The logic is solid, Admin just swapped "A" and "B" in the explanation. This is a good one! Hard to wrap the head around

      Delete
  7. I understand 2 and 3, 3 and 4, 7 and 8, 8 and 9, but why can't we use (4 and 5), (5 and 6), (6 and 7)?

    ReplyDelete
  8. Solutions: A8, B7 : A9, B8 : A2, B3 : A3, B4
    A9 B8 and A2, B3 DO work because…
    If A 9 B8- A says I don’t know, B would know if he had 10, meaning he can only have 8, so A says he knows. The same applies for A2, B3
    A8 B7 and A3, B4 DO work because…
    If A 8, B7 - A says “I don’t know”. At this point, if B had 9 he would know what A is, but since B does not know after hearing A’s first statement, then A can deduce that B does not have 9 and therefore must have 7. The same applies for A 3, B 4
    A8 B9 and A3, B2 DON’T work because…
    If A 8 B9- when A says “I don’t know”, then B would know A had 8. The same applies for A3, B2.
    Too many variables exist for any other answer.

    ReplyDelete
  9. "...numbers between 1 and 10." are: 2,3,4,5,6,7,8,9 . One and Ten should not be included. That's what my math teacher told me long time ago.

    A: I do not know your number.
    (Saying this A is neither 2 nor 9. If A is 2, the consecutive number is only 3 . If A is 9, the consecutive number is only 8.)

    B: Neither do I know your number.
    (Saying this, B is neither 2 nor 9. B is neither 3 nor 8. If B is 3, he will know A, since the consecutive number is only 4 (since A is not 2). If B is 8, the consecutive number is only 7 (since A is not 9).)

    A: Now I know.
    (From B statement, A realized that possibility of B are: 4,5,6,7 only.)

    So if
    A: 3, B: 4 , then A may say "Now I know"
    A: 4, B: 5 , then A may say "Now I know"
    A: 5, B: 4 or 6. A may not yet say: "Now I know"
    A: 6, B: 5 or 7. A may not yet say: "Now I know"
    A: 7, B: 6 then A may say "Now I know"
    A: 8, B: 7 then A may say "Now I know"

    Solutions:
    A: 3 and B: 4
    A: 4 and B: 5
    A: 7 and B: 6
    A: 8 and B: 7

    ReplyDelete
    Replies
    1. very gud interpretation

      Delete
  10. The only possible answer is 2,3 coz ur informed that from the beginning A knew the first number and B knew the second number...since B knows the second number all she has to do is subtract 1from her number to get A's number...but since she admits she doesnt know then it means that her number is 2 because A cannot have 1 as his number coz the question says between 1 and 10...so since they are consecutive numbers...A's number must be 3..but if A's number is 3 then chronologically..his number is the second number..so unless the professor lied to them which is highly improbable...so the only possible solution is 3,4...but if this is the solution with respect to the alphabet..then how comes B didnt know A's number..since they are consecutive she could have simply subtracted 1 to know A's number since her number was allegedly the second ....therefore...any two digit combo between 1 and 10 could be the answer...all we know is that either the professor or B is a liar...the professor could have lied about who's number came first chronologically or B could have lied about not knowing A's number...either way one of them foiled the experiment for us.

    ReplyDelete

  11. A: I do not know your number.
    B: Neither do I know your number.
    A: Now I know.
    Ans : The soln is b/w 1 & 10. So 1 & 10 is eliminated from our calculations. then If 'A' is Having 3 means. A dont know the value of B. Now B is saying 'Neither do I know ur number', means it realized the soln is only b/w 1 to 10. so the next value of 1 is 2 only. Now 'A' realized that B might have 2. So A=3, B=2. Vice versa for 8&9. A=8,B=9.
    Possible Ans is : 2,3 & 8,9

    ReplyDelete
  12. between 1 to 10 means ,
    Number 1 and 10 not included
    so ur ans is incorrect.

    ReplyDelete
  13. between 1 to 10 means ,
    Number 1 and 10 not included
    so ur ans is incorrect.

    ReplyDelete
  14. odd number and even number

    ReplyDelete
  15. Isn't it 5 solutions?
    3-4
    4-5
    5-6
    6-7
    7-8

    ReplyDelete
  16. Either the riddle is badly constructed and not explained clearly or its very BS riddle.

    if all 3 of them know that professor thought consecutive numbers and A knows his number so where is the scope of a riddle in that? B has A+1.

    ReplyDelete

  17. From first statement of A
    ....DAT means A Choose numbers from 3 to 8.

    From second statement by B....B numbers are 4567.

    So if A is 3 den B is 4.
    And if A is 4 den B is 5.

    IF A is 5 we can't say which number is B.( but A says I know now)
    Same with 6.

    If A is 7 den B is 6.
    If A is 8 den B is 7.

    Ans:

    34
    45
    76
    87

    ReplyDelete

  18. From first statement of A
    ....DAT means A Choose numbers from 3 to 8.

    From second statement by B....B numbers are 4567.

    So if A is 3 den B is 4.
    And if A is 4 den B is 5.

    IF A is 5 we can't say which number is B.( but A says I know now)
    Same with 6.

    If A is 7 den B is 6.
    If A is 8 den B is 7.

    Ans:

    34
    45
    76
    87

    ReplyDelete