Confusion of rotten/healthy in #Notation section. Section should be:

Notation

Suppose that in some forest, 40% of the trees are rotten and 60% of the trees are healthy. There are then 2 rotten trees for every 3 healthy trees, so we say that the relative ratio of rotten trees to healthy trees is 2 : 3 (note that the ":" doesn't signify "division" as it would in French or German). If we selected a tree at random from this forest, the probability of getting a rotten tree would be 2/5, but the odds would be 2 : 3 for rotten vs. healthy trees.