I would do it like this...

A1 = Total available
B1 = First amount drawn
C1 = 2nd amount drawn
D1 = IF(OR(B1A1,C1B1),"error",B1/A1*C1/A1)

Beware as the above from a one statistics class student.
'---
Jim Cone
Portland, Oregon USA .
http://www.mediafire.com/PrimitiveSoftware .
(Lottery Numbers workbook: two national lotteries & twelve state lotteries - in the free folder)




"Jake"
wrote in message
...
If I have A2 numbers in a pot and I select B2 of them, then draw out C2, how do I write a formula
that will calculate the chance of the number of numbers drawn in C2 matching (some or all,
depending on whether B2 = C2, but B2 is always = C2) the number of numbers in B2?

Example 100 balls, 100 to match, 100 drawn - chances are 1:1 that there will be a match - or just
displayed in an cell 1.

I know how do do the chance that A2 ball in B2 will match by using =COMBIN(B2,A2) but thats
different to what I'm asking.