There are three guards and three prisoners who need to cross a river. Their boat only holds two people at a time, and the number of prisoners must not be allowed to outnumber the number of guards on either side of the river; otherwise, the prisoners will overpower the guards and, well, the story will come to an abrupt end.

Determine how many trips it will take to safely transport all of the guards and prisoners across the river, list each of the trips that need to be made and who is in the boat and who is on each of the riverbanks during each trip.

A wealthy wise old woman feared that her son was lazy and as a result rather stupid. When the old woman died, her will stipulated that her assets were to be liquidated and a cheque was to be written for the full amount. The check was to be placed in one of three envelopes. The other two envelopes would contain a blank piece of paper. If the son could determine from the writing on the envelope which envelope contained the cheque, he would inherit her mother’s fortune. Otherwise, the fortune would go to the old woman’s favourite charity for animals. The son was not allowed to touch the envelopes. Her decision had to be made based on the writing on the envelopes. The son was told that only one envelope had a true statement and that the other two statements were false. The envelopes had the following writing: 1. This envelope does not have the cheque 2. This envelope has the cheque 3. The second envelope does not have the cheque Which envelope should the son pick ?