MATH10120 Midterm: Math10120F14 Practice Exams F14 MATH10120PracticeSol1
Document Summary
The 16 members of the hat eld family and the 18 members of the mccoy family have. However, they still hate each other, so the hat elds only shake hands with other hat elds, and the mccoys only shake hands with other mccoys. If everyone shakes hands with all other members of his/her family, how many handshakes take place? (a) 18! (b) c(16, 2) + c(18, 2) (c) c(16, 2) c(18, 2) (d) P (16, 2) p (18, 2) (e) There are two kinds of handshakes: hat eld handshakes and mccoy handshakes. The number of hat eld handshakes is c(16, 2). The number of mccoy handshakes is c(18, 2). So the total number of handshakes is the sum of these: (5 pts. ) Which of the following is not equal to c(n, r)? (a) n! r! (n r)! (d) c(n, n r) (b) (e) (n)(n 1) (n r + 1) r! (c) P (n, r) r! (n r)! r!
