1) how many ways can six books be arranged on one shelf? a) 21 b) 120 c) 360 d) 720 2) there are eight girls competing in an ice-skating competition. in how many ways can they finish in first, second, and third place? a) 336 b) 1,680 c) 2,016 d) 40,320 3)how many ways can a president and vice president be selected from a class of 12? a) 23 b) 72 c) 132. d) 1,320 4)how many ways can seven students line up for a class picture? a) 5,040 b) 210 c) 28 d) 7