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Old 10-30-2004, 09:08 PM   #6 (permalink)
molloby
Tilted
 
Location: Sydney, Australia
I think I've got it:

There are 80C8 unique ways of choosing 8 balls from 80 and 70C8 ways of choosing 8 balls from 70. So:

Number of with defects = Total number of choices - number of choices without defects

= 80C8-70C8
=19,547,718,623

Enjoy.
molloby is offline  
 

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