(20 votes, average: 4.25 out of 5)Lonnie is taking the train to the Library. He tells Rosti the hour of his train’s departure and he tells Ann at which minute it leaves. He also tells them both that the train leaves between 0600 and 1000.
They consult the timetable and find the following services between those two time: 0632 0643 0650 0717 0746 0819 0832 0917 0919 0950
Rosti then says “I don’t know when Lonnie’s train leaves but i am sure that neither does Ann”
Ann Replies “I didn’t know his train, but now i do”
Rosti responds “Now I do as well!”
When is Lonnie’s train and how do you know?
Check your answer:-
Answer: 0917
Explanation: This is little tricky one.
As Rosti is sure that Ann also don’t know, for all the times of that hour, minute is clashing with some other hour.
So it can’t be 07th hour as 46 is unique to that hour.
So remaining times are
0632, 0643,0650
0819, 0832
0917,0919,0950
Now, after the first statement Ann could figure out the correct time, so remaining times are not that important but the one which is rules out with 07th hour is more important i.e. 0717.
Ann must already be knowing that train leaves at X hour 17 minutes and earlier she was confused between 0917 and 0717, but now 0717 is rules out so it must by 0917 and she knows the time.
And with the same Logic, Rosti could also figure out that time is 0917.
