Question
Assume that one person can carry a four day supply of food and water for a trip across a desert that takes 6 days to cross. One person cannot make the trip alone because the food and water would be gone after 4 days. How many persons would have to start out in order for one person to get across and the others to return to the starting point?
Answers
oobleck
google is your friend. Here is one solution of several:
https://www.algebra.com/algebra/homework/word/coins/Word_Problems_With_Coins.faq.question.775914.html
https://www.algebra.com/algebra/homework/word/coins/Word_Problems_With_Coins.faq.question.775914.html
Reiny
Have seen this in an old math book.
You start with 3 people.
At the end of first day, the 3 people now have 3 days' food each, one person give a days' food to the other two, so 2 people now have 4 days' food and the 1st has a days' food left and heads home.
At the end of day 2, the 2 people each have 3 days' food, so one gives a day's food to the other. Now, the one with 2 days' food heads home, and the one with 4 days' food has 4 days to get to the other side.
You start with 3 people.
At the end of first day, the 3 people now have 3 days' food each, one person give a days' food to the other two, so 2 people now have 4 days' food and the 1st has a days' food left and heads home.
At the end of day 2, the 2 people each have 3 days' food, so one gives a day's food to the other. Now, the one with 2 days' food heads home, and the one with 4 days' food has 4 days to get to the other side.
Reiny
same source as mine
No page seems to have a valid algebraic solution.
No page seems to have a valid algebraic solution.