Afish tank contains 16 gold fish and 24 guppies . if you already selected 2 fish, what is th e probability that they are both gold fish

There are 16 + 24 fish in total.
The first goldfish is chosen with a probability of 16/40. The second goldfish would then be chosen with a probability of 15/39 since you already chose a goldfish.
Multiply the two probabilities together:
16/40 * 15/39 is around 0.154