MATH10120 Midterm: Math10120F14 Practice Exams F14 MATH10120Practice1
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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) P (16, 2) + p (18, 2: (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! There are 11 members of a club, and they need to choose a president, a vice president and a treasurer (who are di erent people).