although the rules of probability are just basic facts about percentages or proportions, we need to be able to use the language of events and their probabilities. choose an american kid (between 8 and 12) at random. define two events: the chosen child is obese the chosen child is overweight but not obese according to the national center for health statistics, the probability of a child being chosen is obese is: and the probability that the chosen child is overweight but not obese is p(b)