A pilgrim needs to make a journey on foot between Casablanca and Marrakesh, to deliver movies to the new Marrakesh multiplex. It's an arduous and dangerous trip at best, and it takes six days. The most a traveler can carry for food and water is four days' worth.
I hope there's a hotel someplace in between.
There are no hotels. Here's the question: How many people must start out together, so that one of them can make it all the way to Marrakesh from Casablanca?
One other thing: the others who start out along with the pilgrim? They can't die along the way.
Why did the vector cross the road?
It wanted to be normal.
x + (6 - x) + n2x < (n+1)4
6 + n2x < 4n + 4
2 + n2x < 4n
where n is the number of additional people that turn back.
and x is the number of days they travel before giving food to the loner to finish.
igloo myrtilles fourmis