[no subject]

             exp(child*b4 + camper*b5 + b6) 
   P(n=0)= ---------------------------------- 
           1 + exp(child*b4 + camper*b5 + b6)

Note that this could be characterized as the probability of not attempting 
to catch fish. It follows that 1 - P(n=0) is the probability of attempting 
to catch fish.