Suppose that we are $6$ guests for renting a house, $2$ are going to spend three nights in the house while $4$ of them are going to spend just $2$ nights in this house. The problem is that if the bill of renting this house is $x$, how can we share it? Two possible solutions are proposed:
- The total of nights for the group is $$3+3+2+2+2+2=14,$$ so the people who are going to stay in the house $3$ nights have to pay $3x/14$, the rest $2x/14$.
- One night is totally paid for the $2$ guests $x/3$ and they also have to pay the proportionally part of the two following nights $(2x/3)/6$. The rest only have to pay these last nights $(2x/3)/6$.
The thing is that for an arbitrary $x$ the payments are different for the people. In the first case is not fair for the $2$ nights guests because they are sharing the total amount, but this is the most reasonable solution because they pay exactly $2/3$ less than the $3$ nights guests. However, the $3$ nights guests have to pay considerably more amount in the second case (2.5 times more) than the $2$ nights guests. Which one is the correct answer?