Question 1078048
The number of possible samples is 600C20.
None would be 596C20
For 1 it would be 4C1*596C19=0.1210; 4 ways to choose the affected passenger, 596C19 the number of ways to select 19 from 596.
For 2 it would be 4C2*596C18=0.006
For 3 it would be 4C3*596C17=0.0001
0.1219 would see it and 0.8781 would not see it.  Note, one could multiply (596/600)*(595/599)*...*(577/581) as well, which gives 0.8729, and likely with some error, since by fractions, there has to be rounding and by multiplying all the numerator and denominator terms, one is dealing with 10^56.