You're standing in front of a square mirror that's 300 mm on a side. There's a tiled wall behind you in which the tiles are squares 150 mm on a side. When you look in the mirror, you see exactly 25 of these tiles--or rather you would, if your body didn't get in the way of some of them.

Without being told the width of the room, identify what fraction of the way from the mirror to the tiled wall that you are located.

(In reply to Solution by Hugo)

I did this the same way, imagining I was behind the mirror.  In my calculation though I am 40% of the distance to the mirror and then to the back wall.  I would thereofre be 40/60 of the length of the room from the mirror if I was in front of the mirror.

This assumes also that I am looking through one eye which is central to the mirror, and that there is no grout between the tiles!

Posted by Fletch on 2005-01-13 14:13:49