Probability question with a definite outcome

#1
So I'm having trouble calculating the probability of the following scenario:

I have 4 possible locations for 4 boxes. Each of these boxes may exist with a probability, β. There is also a circle, this circle definitely exists.There can only be one connection between the circle and the the locations of boxes (i.e. the circle can only be connected to one spots for the boxes). What is the probability that the circle is connected to a spot with a box which does not exist?

Attempt at solution:

So I figure that i would need to multiply the probability that there is only one connection by the probability that that box doesn't exist. The only problem is that I couldn't figure out which probability I am supposed to put in the binomial equation, because I can't put in (1-β) as p because then q would be β, but it doesn't matter to me that all the other boxes exist, all I care about is the box with the connection exists. And then I thought to put in the probability that there is one connection in for p, but then I got 1 and q is 0. So I am really not sure what to do...
 
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Dason

Ambassador to the humans
#2
Hi! :welcome: We are glad that you posted here! This looks like a homework question though. Our homework help policy can be found here. We mainly just want to see what you have tried so far and that you have put some effort into the problem. I would also suggest checking out this thread for some guidelines on smart posting behavior that can help you get answers that are better much more quickly.