Ferrari Mailing List: Re: birthday greetings

[Hans E. Hansen (FList]

Thread hijack:

In college days I used to fleece money from unsuspecing passengers
by betting them that within the next 20 cars, there will be two whose
last 2 digits match.  ie - a match could be ABC123 and DEF523.
Without punching the numbers, I think the breakeven point on this
was around 16 cars.  It would very often go to at least 18 before a
match.

What was especially neat is that often you could get odds, as
we are only talking about looking at 20 cars and there are 100
possibilities. Hehe.  I usually would start the proposition that we
would look at the next 50 cars, as that should be 50/50 odds, right?
But then "for practicality" sake, it got reduced to 20.  After losing the
first bet, the victim would often want to do it again to try and get his
money back.

Hans.

On 12/17/06, Pat Scopelliti <pscopell [at] stny.rr.com> wrote:
> Close, but no.  Wait until you have 22 people.  With 20 people you have a
> 44% chance of having two people with the same birthday (assuming 366 days)
> Here are the numbers up to 30 people
>
> 10 13.842700
> 11 16.432100
> 12 19.172000
> 13 22.043000
> 14 25.024900
> 15 28.097700
> 16 31.241000
> 17 34.434700
> 18 37.659200
> 19 40.895500
> 20 44.125200
> 21 47.331200
> 22 50.497000
> 23 53.607900
> 24 56.650000
> 25 59.611100
> 26 62.480200
> 27 65.248100
> 28 67.906700
> 29 70.449600
> 30 72.871800
>
> Pat
>
> Pat Scopelliti
> pscopell [at] stny.rr.com
> 607-731-8584