juice glasses

Question

Six glasses are in a row. The first three are full of juice; the second three are empty. By moving only one glass, can you arrange them so empty and full glasses alternate?

Answer 1

The 6 glasses are  F F F E E E 

 

If you pick up the 2nd glass and pour its contents into the 5th glass and then replace the 2nd glass to its original position then the 2nd glass will be empty and the 5th glass will be full (assuming the glasses are the same size) so you will be left with  F E F E F E  which alternates.  

Answer 2

If you place the 6 glasses in a row you have

 

F F F E E E     (letting F = full,  E = empty)

 

If you switch the 2nd glass with the 4th glass you get

 

F E F E F E

 

which alternates.  The problem is you actually move 2 glasses... #2 and #4