Ben and Mark are students of Mr Tan. Mr Tan’s date of birth is on N/M/1970 and both of them know that Mr Tan’s birthday is one of these 10 dates:
4/3/1970 5/3/1970 8/3/1970 4/6/1970 7/6/1970 1/9/1970 5/9/1970 1/12/1970 2/12/1970 8/12/1970
Mr Tan tells Ben the value of M and tells Mark the value of N. Then Mr Tan asks them: “Do you know when my birthday is?”
Ben says: “I don’t know, but I can be sure that Mark doesn’t know either.”
Mark says: “Initially I don’t know, but now I do.”
Ben says: “Oh, then now I know it too.”
Based on this dialogue and the dates given, can you figure out which is the correct date of Mr Tan’s birthday?
Riddle Answer