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## Homework Statement

1) S'pose we flip 2 fair coins, and roll one fair 6 sided die. What is the probability that the number of heads equals the number showing on the die?

2) We roll 4 fair six sided dice. What is the conditional prob. that the first die shows 2, conditional on the event that at LEAST 3 dice show 2.

## Homework Equations

P(A|B) = P(A and B)/ P(B)

## The Attempt at a Solution

1) 0.25 / (1/3) = 3/4. Is this correct? I have my doubts. :|

**EDIT**: Now I think it is: (1/3) / 0.75 = 4/9

2) The first of the question asks, if "EXACTLY" 3 dice show 2, in which the answer is 3/4. But for at least 3 show 2, I don't get how to mathematically show it, using the above formula. Intuitively I understand that the prob. has to be greater than 3/4 in this case, just don't know how to show. Any help would be appreciated.

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