Sixteen five gallon containers form a 4x4 grid. Move only ONE container so as to make the row sums, column sums, and main diagonal sums, the same.
[1] [2] [3] [2]
[2] [2] [3] [1]
[3] [1] [2] [4]
[2] [4] [5] [3]
(In reply to
Solution by Federico Kereki)
Oops... I forgot about the diagonals, and since you cannot pour gallons
at will, I found this solution, based on using the container in the
fourth row and third column, which we will empty in other containers.
First, fill the container at the fourth row, second column, leaving 4
gallons in your container. Then, fill the container at the second
row, third column, leaving 2 gallons on hand. Finally, empty your
container at the first row, first column, leaving your original
container empty, which goes back to its place:
1 2 3 2 1 2 3 2 3 2 3 2
2 2 3 1 2 2 5 1 2 2 5 1
3 1 2 4 3 1 2 4 3 1 2 4
2 5 x 3 2 5 x 3 2 5 0 3
Edited on March 20, 2005, 4:07 pm