Mathematical puzzle!

[ArDee]

Square root of -1 is i if you're a mathemetician, or j if you're an electrical engineer - we've normally got enough i values already being used for currents...

j as the square root of -1 is the general form used in all engineering, it's just that imaginary numbers are more common in electrical engineering; but, it’s an engineer vs. mathematician thing.

 

[TheDoctor]

Righty ho.
I'd only come across it in electrical, but that's because I've only studied electrical!!!!!

 

[TheDoctor]

I know, after a while they date so badly...

But I don't give a fig...

It's all dried up now, and i'm grapeful.

[/coat]

 

[marinyork]

All this talk of js is a load of moonshine .

 

[punkypossum]

You change your first choice.

If you have chosen a door the host can then let you open the door with nothing behind it and so you loose. But the host opens the other door that has nothing behind it and so there is an increased probability that there is something behind the remaining door you did not chose.

It is a probability question. Your first choice has odds of 1:3, after the host opens the door the odds change to 1:2 and so you make a new selection.

Don't get it, maybe I'm too thick for this...Why do the odds improve as I change? Cause at the end of the day, all I know at this point is that there is nothing behind the door that the host opens, so no matter if I stick or swap, at this points my odds should be 50/50???

 

[red_tom]

There's a simulator at http://www.grand-illusions.com/simulator/montysim.htm

Give it a go.

Now, will someone give the answer to the £47 taking off shoes thing. It's driving me mad.

 

[User482]

Don't get it, maybe I'm too thick for this...Why do the odds improve as I change? Cause at the end of the day, all I know at this point is that there is nothing behind the door that the host opens, so no matter if I stick or swap, at this points my odds should be 50/50???

See post #30: http://www.cycle-cafe.net/forums/showpost.php?p=372448&postcount=30

 

[punkypossum]

I can see that it works, I just don't understand it...

As for the shoe thing, yes, it's doing my head in as well!

 

[User482]

I can see that it works, I just don't understand it...

As for the shoe thing, yes, it's doing my head in as well!

Well, the point of the puzzle is that it's counter-intuitive! If you look at the link I posted, it explains all the outcomes, and if you work out the likelihood of each outcome, you will see that switching doors improves your odds.

 

[marinyork]

http://en.wikipedia.org/wiki/Monty_Hall_problem#Why_the_probability_is_not_1.2F2

 

[punkypossum]

AHA!!! Get it now! Forgot about the host not wanting to reveal the prize, that makes sense!

 

[jonathan ellis]

Now picture the tank on a treadmill...!

20 top and 0 bottom sox for the delay

 

[punkypossum]

What is the solution to the shoe shop thing then?