Math's Puzzle : Odds

[Board Game Geek]

Hello folks.

Would someone be able to provide an answer to this for me please ?

If 300 people were in a masssive room, and only 65 of those people were called "John" :

What would be the odds of me walking in to that room, silently tapping 65 people on the back, who then leave the room, and outside, they ALL honestly declare, that they are called "John" ?

Any takers ?

 

[threaded]

that'd be

65/300 x 64/299 x 63/298 ...

 

[Board Game Geek]

that'd be

65/300 x 64/299 x 63/298 ...

Thank you Threaded !

I best get Excel fired up and write a formula.

I'll probably do it like this.

65/300 = j1
64/299 = j2
63/298 = j3
drag down

total = j1xj2xj3xetc

Cheers !

 

[Board Game Geek]

And it works out at

1.43565E-67

Hmmmmm.

 

[Board Game Geek]

Ok, so were are talking beyond the realms of winning the lottery here. Which is 14 million or so to 1 I believe.

Can anyone suggest how to put those odds in to perspective for the layperson to understand ?

Eg, chance of an asteroid hitting the Earth, or chance of a monkey writing the complete works of Mr Shakespeare in one sitting, or whatever ?

(I can feel someone saying the chance of X saying something sensible coming on here....)

 

[threaded]

Reciprocal.

 

[Board Game Geek]

Reciprocal.

Huh ?

Okies, off to google we go....

 

[threaded]

Huh ?

Okies, off to google we go....

You need to take the reciprocal so it becomes 1 chance in ...

It's a "balls from bag" problem, so that's what you need to google for.

 

[Board Game Geek]

Riiiiiiiiiiggggght !

So, when bloke in chip shop asks me "So, what was the odds of you picking out thos 65 blokes called 'John' ", I am supposed to reply "It's reciprocal, mate".

At which point he will either deck me, or order curry sauce for his chips and pontificate on life, the universe and everything, and go home, throw away all his football paraphernalia, and either join a monastery or take up an OU course on pure or applied maths ?

 

[Board Game Geek]

Ah balls in bags, I know that one from a magic trick I have, didn't make the link, thank you.

Reciprocal is such a wishy washy answer though, particularly for a layperson.

1 in 300 billion billion billion (as a guess) is a bit more appropriate though. It's
close enough.

Thank you !