A fish tank contains eight algae-eaters, five catfish, and six tilapia fish. A storekeeper randomly selects two fish (one after another without replacement) from the tank for a customer. Find the probability that both fish selected are catfish.
The probability of the first fish being a catfish is 5 catfish out of 19 total fish ⇒519
The probability of the second fish being a catfish is 4 catfish out of 18 total fish ⇒418⇒29
The total probability is 519⋅29=10171
