Logic Riddles

Logic riddles with answers involve looking at situations and making judgements about them by ruling out impossibilities. If you like solving maths puzzles, you will most probably like logic riddles as well.

Three Spies

Three spies, suspected as double agents, speak as follows when questioned:

Albert: “Bertie is a mole.”
Bertie: “Cedric is a mole.”
Cedric: “Bertie is lying.”

Assuming that moles lie, other agents tell the truth, and there is just one mole among the three, who is the mole?

Riddle Answer

3 Sacks of 30 Coconuts

An intelligent trader travels from one place to another with 3 sacks having 30 coconuts each. No sack can hold more than 30 coconuts. On the way, he passes 30 check points. At each check point, he has to give one coconut for every sack he is carrying. What is the maximum number of coconuts that he can have with him at the end of his journey?

Riddle Answer

Mr Tan’s Birthday

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