HMMT 2002 G6

If we pick (uniformly) a random square of area 1 with sides parallel to the $x$ - and $y$-axes that lies entirely within the 5 -by- 5 square bounded by the lines $x=0, x=5, y=$ $0, y=5$ (the corners of the square need not have integer coordinates), what is the probability that the point $(x, y)=(4.5,0.5)$ lies within the square of area 1 ?