MATH 151 Lecture 3: September 17th - 1.4-6 Counting, Permutations, and Combinations

• School: University of Victoria
• Department: Mathematics
• Course: MATH 151
• Professor: Jill Simmons

Document Summary

Recall: n(aub) = n(a) + n(b) n(anb) Two sets that don"t intersect are called disjoint ie. anb = . 6(numbers on each die) x 6 x 6 = 216: how many outcomes result in at least two dice showing the same number? (count the complement) Total # of ways to roll total # of ways where they are all different. Permutation: given a set of objects, a permutation of the elements of the set is an arrangement of the elements in a line (order matters) The permutations of set a are: xyz, xzy, zyx, zxy, yzx, yxz. Sometimes, we"ll want to arrange only some of the elements of a set: npr aka n! ( n r) ! How many ways can we select a president. Four couples are to be seated in a row of 8 seats so that each person gets to sit next to their partner.