Mathematical puzzle!

[Speicher]

Close enough, I would have thought he would know if he lived at no 67 or 167.

Well done.

 

[Over The Hill]

OK – how about this…

On a game show there are three doors, behind one is the big prize behind the other two; nothing.

You choose a door.

Host then opens one of the remaining two doors which will always have nothing behind it.

You can now stick with your first choice or change over and choose the other remaining door.

What do you do and why?

 

[Mr Pig]

What's going on?

I don't know, but do people pay to watch?

 

[Rhythm Thief]

OK – how about this…

On a game show there are three doors, behind one is the big prize behind the other two; nothing.

You choose a door.

Host then opens one of the remaining two doors which will always have nothing behind it.

You can now stick with your first choice or change over and choose the other remaining door.

What do you do and why?

Stick with your first choice. If one of the remaining two doors can be guaranteed to have nothing behind it, it follows that the other one must also have nothing behind it. Otherwise, how could the outcome of opening the first of the remaining doors be guaranteed? I think.

 

[Night Train]

Oh maths...in secondary school we had a student teacher for a couple of lessons - he was going on about the square root of -1, which apparently may or may not exist.

Square root of -1 is i and it's negative is j IIRC.

The top of a rolling wheel is at twice the axle velocity while the bottom is at zero.

 

[Night Train]

OK – how about this…

On a game show there are three doors, behind one is the big prize behind the other two; nothing.

You choose a door.

Host then opens one of the remaining two doors which will always have nothing behind it.

You can now stick with your first choice or change over and choose the other remaining door.

What do you do and why?

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.

 

[TheDoctor]

Square root of -1 is i and it's negative is j IIRC.

The top of a rolling wheel is at twice the axle velocity while the bottom is at zero.

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...

 

[Arch]

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...

As in "this fruit cake contains i currents..."?

 

[TheDoctor]

As in "this fruit cake contains i currents..."?

Electrical currents. Should have guessed someone would start raisin that one...

 

[Speicher]

I was going to mention currants, but now Arch has scone and done it.

 

[cisamcgu]

A man walks into a shop with a £20 note. He tells the shopkeeper his name. The shopkeeper hands him a bag, takes the £20 note, and gives him a credit note for £47. The man takes his shoes off and leaves, via the back door.

What's going on?

No idea ... please tell

 

[User482]

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.

Nearly correct - when you switch, the odds of winning are 2/3. This is the famous "Monty Hall" puzzle: http://www.open2.net/sciencetechnologynature/maths/montyhallproblem.html

 

[Melvil]

I was going to mention currants, but now Arch has scone and done it.

We'd butter stop these currant puns now whilst the going is still pud.

 

[Arch]

We'd butter stop these currant puns now whilst the going is still pud.

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

But I don't give a fig...

 

[marinyork]

The Monty Hall problem is isomorphic to other earlier puzzles but getting famous coverage . There are some wacky basic puzzles on here http://www.puzzle.dse.nl/math/index_us.html