Question

Eliana is shopping for a wedding gift for her friends, who have registered at a department store. Some of the items on the registry have already been purchased by other wedding guests.

Are these two events dependent or independent?

Answer 1

Dependent. When other guests buy registry items they change what remains available, so the probability that Eliana finds (or picks) a particular item depends on those prior purchases. (If items were somehow “replaced” after purchase the events could be independent, but in the usual registry situation purchases are without replacement, hence dependence.)