I have 4 unbiased dice with 6 sides.

1) I want dice1 to have value "1" and any values from the other 3 dice.

Ans: 1/6 x 1 x 1 x 1 = 1/6

2) I want at least 3 dice to have values "1"

Ans: 4c3 x 1/6 x 1/6 x 1 x 1 = 1/9

3) I want at least 3 dice with the same values (any value as long as it's the same)

Ans: 4c3 x 1/6 = 2/3

Need some help to check if my understanding of probability is correct. It has been a long time since I worked on this topic. I think I might be wrong with no.3 or if I'm wrong with any, please advise.

Thanks!