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Heres one of those mental puzzles where you just kick yourself when you find out the answer.

Here Goes then...

The scenario is you are standing outside a room which you canot see inside. On the wall infront of you there are 3 light switches each controlling a light inside the room.
The challange is, is to find out which switch turns on which light.
The catch is you are only allowed to enter ther room once.

Enjoy

OK.....
Turn switch 1 and leave it on for ages, but don't go into the room. Switch off switch 1 + turn on switch 2.

Enter the room.

If it's dark in the room then trip over assorted furniture and find the bulb. If the bulb is hot, then switch 1 is the correct switch. If the light is on in the room then switch 2 is correct. If it's dark in the room and the bulb is cold then switch 3 is correct.

Why are round manholes better?

Okay, I'm stumped so I'm going to have a guess, you never know, it could be right. Stand in the room but put your arm round the wall and switch each of the switches on one at a time. Or, switch each switch and look into the room, do not enter it.

you never said you could'nt have afriend in the room whatching for the light as you go throught the sequence did you?.

So to clarify?

Inside the room there are 3 lights
Outside has 3 switches
Each switch will turn on one of the Lights.
Each switch starts off in the Off position.

If this is the case, then I think fletch is correct.
a) Turn on Switch 1 and 2 and leave them on for 10 minutes
b) Turn off switch 2
c) Enter the room.

d) The light that is on is powered by switch 1
e) The hot light that is off is powered by switch 2
f) the cold light that is off is powered by switch 3.

As for the manhole cover - they are round to stop them from being able to fall in the hole. A square/rectangle cover would be possible to fall in (along the diagonal) whereas a round one can not.

I misread the initial post. I thought there was only 1 light in the room. Bananafish's answer works though.

OK, here's another. What is the next line of numbers in the sequence?

1
11
21
1211
111221
312211
13112221

Yep! Banafish you have it in 1!

And would the next series of numbers be?

1
11
21
1211
111221
312211
13112221
13321211<--?
11121221<--?

I think?? Perplexing!

Nope.

Does it have something to do with right aligning the numbers though?

"Does it have something to do with right aligning the numbers though?"

No, but thinking away from the purely mathematical may be of help....

Ok this has got to be it..

1
11
21
1211
111221
312211
13112221

1113311211<---- or 113311211 cant decide which.

Am i going along the right tracks using a type of binary?

Sorry Andy, way off track. I'll let you stew a little while longer. You will kick yourself.

Hint: you only need to be barely numerate to get this one....