Question: Mr. X wants to send Diamond Necklace to his fiancee Y who lives in some other country. Mr. X puts the Diamond Necklace inside a box to parcel. Note that: 1. The parcel must be locked.
2. The box is made up of such a material that nobody can break it.
3. The box has a handle large enough to put a lock on it.
4. Mr. X can not send a key with the parcel.
5. Combination locks and telephones are not available.
How will Mr. X send Diamond Necklace to his fiancee Y?
Answer:
Mr. X and his fiancee Y will follow the following steps.
1. Mr. X will put Diamond Necklace inside a box and will lock it.
2. He will send the parcel to his fiancee Y, without the key.
3. Y will put her lock on it and will send box back to Mr. X.
4. Mr. X will remove his lock and will send the box back to Y.
5. Y will remove her lock and will receive the Necklace.