Question 333173
let x=number of balls whose number is >= 17
--
we want 
in a sample without replacement
P(X>=1) = 1-P(x=0)   (Getting at least one is the same as the complement of getting none)
---
P(x=0)=P(all 3 are numbered <17) ={{{(16/20)*(15/19)*(14/18)=0.491}}}
P(X>=1)=1-0.491=0.509
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This could also be solved as
{{{1- 16C3*4C0/20C3  }}}