posted on Sep, 23 2007 @ 11:51 AM
these came from a book that i've been reading. if you've already heard these and know the answers, then..good for you. ok here we go.
riddle # 1: the light bulb problem.
imagine you are outside a closed room with no windows and one door. you cannot see inside the room until you open the door.
there are 3 light switches in front of you. each switch is connected to a different one of 3 light bulbs inside the closed room. all the light bulbs
are currently off and thus all 3 switches are currently in the off position. you may flick on and off any of these switches as much as you like UNTIL
you open the door and go inside the room to witness the state of the light bulbs. at that point you may no longer change the switches.
you may only open the door ONCE. THEN you must be able to tell which switch is connected to the light bulb.
in this scenario, how can you, with 100% certainty, tell which switch goes to which light bulb?
riddle # 2: the burning string problem
you have 2 lengths of string, which although they are not the same length, will each take exactly 30 mins for a flame to burn from one end of the
string to the other. the strings do not burn evenly, so the position of a flame, as it burns through a string, will not afford you any specific
knowledge of how much time the string has been burning for. all you know is that it takes exactly 30 mins for a flame to burn from one end of each
string to the other end.
without using a timepiece, how can you use these 2 strings and matches to measure out exactly 45 mins with almost perfect accuracy?