Page 102 - NUMINO Challenge_C2

Problem solving Key Points

1 Find the number of outcomes according to the Draw a tree diagram
conditions given below. for each case.

Write A, B, C, and D in order.
Write A to the left of B.
Do not write B next to C.

2 Susan lives on an island and there is no boat Find the number of
that goes directly to the mainland from Susan’s outcomes by
island. The diagram below shows the boat routes drawing a tree
near Susan’s island. Find the number of ways diagram for each
Susan can go to the mainland from her island. case in which Susan
(Note that Susan can use each route only once.) goes to islands B
and C first.

Mainland

C

A B Susan’s Island

99Number of Outcomes