Saint Leo University Tree Diagram and Permutation Equation Worksheet

I’m working on a probability multi-part question and need an explanation to help me study.

At a conference the 100 delegates were asked to rank three possible menus (A, B and C) in orderof preference for dinner. All the delegates completed this ranking.55 ranked A above B; 65 ranked B above C; 35 ranked C above A.B was ranked first by 40 delegates.(a) Megan correctly deduces that the number of delegates who ranked the menus in the orderCBA is 5.Explain how she can know this. [1]…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

30 delegates ranked A third.

(b) Deduce the number of delegates who chose each of the other five possible orders ofpreference.

ABC = 25

ACB = 25

BAC = 15

BCA =25

CAB = 5