Puzzle of the Day : 37
Secret Documents
A businessman in one city needs to send secret documents to his business associate in another city. There are spies trying to get hold of these documents. The documents need to be sent in a case. If the documents are sent in an unlocked case then the documents will be stolen. Anything else in an unlocked case will also get stolen. Both of them have many locks and many cases. Neither of them has the keys to the other person’s locks. How does the businessman send the documents?
The businessman puts the documents in the case, locks it and sends the case to his associate. He keeps the key to the lock with himself. The business associate, when she receives the case, puts her own lock on the case (in addition to the lock already on it) and sends it back. She also keeps the key to her own lock with herself. When the businessman gets the case, he removes his own lock and sends the case back. Once the associate receives the case again, she can unlock it with her key and retrieve the documents.
Case 1 (If cases can be locked without the use of keys)
Businessman in the 2nd city can send unlocked empty case and the BM in 1st city send the documents in it after locking it.
Case 2 (If cases cannot be locked …..)
Not possible