Quote:
Originally Posted by Hamlet53
Transport back in time before automobiles & roads, trains & railroad tracks, and airplanes existed. A message must be delivered on foot across the Sahara Desert from Casablanca to Marrakesh. One person can carry enough food and water to last four days of traveling. The total journey requires six days. What is the minimum number of people that must start on the journey together in order for at least one person to to make it to Marrakesh while leaving nobody stranded in the desert without food or water? Explain your reasoning please.
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Three
They set out on the first day with 12 days rations, and use up 3 days rations, leaving them with 9 days, and one days travel from Casablanca
On the second day, one turns back with 1 days rations, and the other two carry on, each with four days rations. The one who turned back arrives back in Casablanca safely, having used up the 1 days rations. The other two use up two days rations, leaving them with six days, and two days travel from Casablanca
On the third day one turns back taking two days rations, and the remaining traveller carries on with four days rations.
At the end of the fourth day, the second traveller arrives safely back in Casablanca.
At the end of the sixth day, the third traveller arrives safely in Marrakesh