There are 6 mushrooms in the basket, 3 of them are poisonous. 3 mushrooms are removed at random.

There are 6 mushrooms in the basket, 3 of them are poisonous. 3 mushrooms are removed at random. What is the probability that out of 3 randomly selected mushrooms will turn out to be: a) all poisonous b) 2 poisonous, and one edible c) at least 2 poisonous mushrooms

A big event consists of two small independent ones, here is its formula:
P (C) = P (A) * P (B)

We have several big events, it is easier to find the probability that there will be a poisonous mushroom and an edible

To find a small event:
P (A) = favorable outcomes (m) / number of total outcomes (n)

There are 6 outcomes in total, because 6 mushrooms.
P (i) = 3/6 = 0.5 (3 because poisonous, these are favorable for us)
P (n) = 3/6 = 0.5 (3 edible mushrooms, since 3 are poisonous, and in total we have 6 (6-3 = 3), these are favorable for us)

Now it will be substituted for the task.

A.
Big event: 3 chosen mushrooms at random will be all poisonous
Substitute in the formula and get:
P (C) = 1 poisonous mushroom and 2 and 3
And- multiplication
We get:
P (S) = P (i) * P (i) * P (i)
We have already learned the probability above, we just substitute it.
P (C) = 0.5 * 0.5 * 0.5 = 0.125

B.
Big event: 3 chosen mushrooms at random turn out to be 2 poisonous and one edible
Substitute in the formula and get:
P (C) = 1 poisonous mushroom and 2 and 3 edible mushrooms
And- multiplication
We get:
P (S) = P (i) * P (i) * P (s)
P (C) = 0.5 * 0.5 * 0.5 = 0.125