There are two bulbs in the first floor of a house. There are 3 switches in the ground floor. So, obviously, only 2 of the switches work. How can you find out which switch turns on which bulb? You can go upstairs only once to check.
2007-04-17 23:33:32 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Turn on one switch, wait a couplu of minutes, turn it of and turn on another.
Go to the room and check which bulb is lit and which one is warm.
The one that is warm but not lit is turned on by the first switch.
The one that is lit is turned on by the 2nd.
If no bulb is lit, than the third switch turns on the bulb that is not warm.
2007-04-17 23:40:33 · answer #1 · answered by Amit Y 5 · 1⤊ 0⤋
1. Switch on 2 of the 3 switches.
2. Switch off 1 of them.
3. Go upstairs and if
i. 1 light bulb is on, then the switch you did not switch off controls it. The switch you turned off does not work.
ii. None are lit, but one of them is warm. This means that the warm bulb is controlled by the switch you had switched off. The switch you left on does not work.
iii. 1 light bulb on, 1 warm light bulb. The switch that is left on controls the glowing one, the turned-off switch controls the other.
2007-04-18 07:02:21 · answer #2 · answered by Jeremy 2 · 0⤊ 0⤋
basically If only two swiches work. a light switch creates a blue flash behind the wall plate .when you turn it on in the dark, so you turn each one on and find out which two flash and that tells you which two works. then turn one on and go look and there's your answer.
2007-04-18 06:51:56 · answer #3 · answered by johnnyleadguitar 2 · 1⤊ 0⤋
Not enough information....
2007-04-18 07:11:08 · answer #4 · answered by salai_arasu_m 2 · 0⤊ 1⤋