There are 12 slate rocks, 17 pumice rocks, and 8 granite rocks…

There are 12 slate rocks, 17 pumice rocks, and 8 granite rocks randomly distributed in a certain field. If 2 rocks are chosen at random and without replacement, what is the probability that both rocks will be slate rocks?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #38643