Probability of a Pair of Fish!

Hi, everyone. Thanks in advance for your help

I am involved in the tropical fish hobby and we often go to auctions to purchase fish to breed. Which means we need a PAIR.

My assumption is that when purchasing a bag of 3 fish, the BUYER has a 50% chance of getting a pair. The BUYER could have: all males, all females, a trio (1 male 2 females) or a reverse trio (2 males 1 female).

A fellow stat friend of mine says this is wrong as the placement of each fish in the bag by the SELLER creates a probability event for each fish that should be accounted for. His view is that the odds of getting a pair is much higher: 75%.

Thoughts and/or help appreciated! - Ted


Ambassador to the humans
Imagine pulling out the fish one by one. There are 8 possibilities for the male/female combo (MMM, MMF, ..., FFF). You can enumerate them and see which proportions of the combos give you a male/female pair.


Active Member
could be that the fish monger jest intentionally makes the fish bags of the 4 types in equal proportions and passes them out as such, then wagtail is right.

hed have some fish left-over though.
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