21-Dec-99 03:41 Klaus Weide wrote:
> On Tue, 21 Dec 1999, Doug Kaufman wrote:
>> The error would have been obvious to me a few years ago, without
>> anyone having to point it out.
>>
>> Correct formula for chance of duplicate values (20 from pool of 10000)
>>
>> 1 - ( 9999! / (9980! * 10E76 * 20!))
> You should have trusted your first instinct. :)
Yes, right formulae is
1- (1-1/10000)*(1-2/10000)*...*(1-19/10000)
which is nearly the same as Philip Webb pointed out
(a linear term of the expansion above):
(1+2+3+...+19)/10000 = 19*(1+19)/2*10000 = 190/10000
