Name:      

Directions: Show all work. Unless otherwise directed, you may leave your answer in terms of factorials, falling factorials, and binomial/multinomial coefficients. Any sums or products should be as simple as possible.

  1. [2.5 points] How many 3-element subsets of {a,b,c,d,e,f,g,h} are there? Give an explicit numerical answer.
  2. [2.5 points] A group of 50 people must be split into two teams of size 5 and five teams of size 8. How many ways can this be done?
  3. [2.5 points] A random lattice path of length 2n is generated by starting from (0,0). At each step, we increase the x-component by 1 with probability 12 and we increase the y-component by 1 with probability 12. What is the probability the lattice path ends at (n,n)?
  4. [2.5 points] A standard deck of cards has one card for each of the suit/rank pairs. The suits are spades, hearts, diamonds, and clubs; the ranks are ace, 2 through 10, jack, queen, and king. What is the probability that a poker hand (i.e. a set of 5 cards) has at most 2 cards in each suit?