A forest type consists of three species of trees:
- 25% are Douglas-fir
- 40% are Hemlock
- 35% are Western Red Cedar
a) What is the probability that a tree selected at random will be a Douglas-fir?
b) What is the probability that a tree selected at random will not be a Hemlock?
c) If it is known that the tree selected is not a Hemlock, what is the probability that it is not Western Red Cedar either? (Hint: start with a Venn diagram that uses the entire sample space)