There were 23 people at my last Arachnophobics (fear of spiders) Anonymous' Halloween party. As a gag fake spiders were put into the gift boxes to be handed out when people came in. However, some ...... person decided it would be funny to replace the fake spiders with real spiders in 9 of the boxes. Since my three friends and I agreed to open our boxes together at the coffee table, what is the probability that:
a) all four of our boxes contain a real spider?
b) none of them contain real spiders?
c) at least one of them contains a real spider?