Probablity

Question 1

52 card problems

Answer 1

choose the two ranks
choose 2 from 4
choose 3 from 4
choose final rank
choose one from final

OR

choose rank 1
choose 2 from 4
choose rank 2
choose 2 from 4
choose rank 3
choose 1 from 4

divide by 2 b/c rank1,2 can be flip flopped but counts the same

Question 2

What is the probability that, in a group of 30 people, at least some pair share the same birthday? Assume 365 possible equally likely birthdays.

Answer 2