Quick maths question

[OMGMOO]

If I have a choice of three things, but I only have a coin to help me in my decision is it an equal chance between all three options if I flip the coin between option 1 & 2, then loser plays 3 & then again with the winners of match 1 and 2 and whoever wins match #3 is the one I pick?

And if not, is there any other way to give all three options the 33% chance of winning? btw It's not a homework question or anything I was just wondering and cannot be bothered to work out the odds myself xD.

 

[Eclectic Dreck]

No.

Option 1 and 2 have a 25% chance of success. Option 3 has a 50% chance.

The reason is simple enough:

On the first flip, option 1 and 2 have a 50% chance of occurring. The winner then goes against option 3. The winner of the first flip and option 3 each have a 50% chance to win, but the winner of the first flip has already undergone a similar trial. Thus, by being tested more often than option 3, it has a reduced probability of occurring when examining the test in total. For the test to be fair, each coin in each test must have been tested the same number of times at the same odds.

 

[sidhe3141]

Have 1 and 2 flip, then 2 and 3, then 1 and 3. If each wins one, do the thing over until someone wins both of their flips.

 

[Dags90]

Make a three sided die out of a Toblerone, be sure to throw it up really high though.

 

[The Blue Mongoose]

Roll a 6-sided die. 1 and 2 = Option 1, 3 and 4 = Option 2, and 5 and 6 = Option 3.

 

[Tears of Blood]

Oh just pick one, d00d.

 

[Aurgelmir]

Have 1 and 2 flip, then 2 and 3, then 1 and 3. If each wins one, do the thing over until someone wins both of their flips.

This is probably the better option, if all you can use is a coin.

If you have other methods do things like:

Roll a 6-sided die. 1 and 2 = Option 1, 3 and 4 = Option 2, and 5 and 6 = Option 3.

or just write all three options down on a piece of paper and have a random draw.


(I wonder if this thread is doing his homework for him? )

 

[Mr. Cheese]

Sacrifice six babies and a virginal woman under the red moon whilst chanting the Prayer of Lament after performing the Ritual of the Black Ram and the decision will be made by Slaak Tharm, Baron of Death.