Help me please: difficult problems
I got an exam tomorrow and I just found this website I shoulda found earlier. Please help me if you know how to do these problems:
1. If 3 people are picked from a group of 4 married couples, what is the probability of NOT including a pair of spouses?
2. Find a formula for the probability that EXACTLY one of the events A, B, or C occurs. Then, make up a problem and solve the problem using the formula.
3. Find the probability of getting three of a kind in a regular poker (excluding 2 jokers so there is 52 pokers)
a) 3 of a kind means KKK A 2
My answer is [(13C1)*(4C3) + 2*[(12C1)*(4C1)]] / (52C5)
b) full house: [(13C1)*(4C3) + (12C1)*(4C2)] / (52C5)
c) 4 of a kind: [(13C1)*(4C4) + (12C1)*(4C1)] / (52C5)
What do you guys think?