Imagine an enclosed box divided into 2 with a hole in a wall that divides the 2 halves. Each half has some marbles and some golf balls in it. The hole is only big enough to let a marble go through. One half has got say, 2000 marbles and 50 golf balls. The other half has got 2000 marbles and 20 golf balls. Now shake the box.
The 2 halves will have still have the same number of golf balls but more marbles will travel from the ’20 golf ball side’ to the ’50 golf ball side’ then will travel from the ’50 golf ball side’ to the ’20 golf ball side’.
You must decide what the box, marble, golf ball and wall with a hole represents.