Warm Up. Suppose we wanted to sit six people, three men and three women in a row of six chairs. How many ways can we seat them if we must start with a woman and then alternate women and men? 72 How many ways can we form a license plate if we want three digits followed by two letters?
(n – r)!
r! r! • (n – r)!
P(16, 2) x C(14, 3) = 87,360 ways.
210 x 220 = 46,200
90 x 56 = 5,040