Another way of expressing probabilities is by the use of odds. Suppose I roll a single die and call getting a 4 a favorable outcome. The probability of this happening is of course 1/6, which means that we expect to see a 4 once out of every six rolls. But this can also be expressed in terms of odds. Here's how it works: There are six possible outcomes; one of these is
favorable (getting a 4) and five are unfavorable. One then says that the odds against getting a 4 are 5 to 1. This could also be expressed by saying the odds in favor of getting a 4 are 1
to 5
In general, if we list all the possible equally likely outcomes, the odds in favor of a favorable outcome are expressed as the number of favorable outcomes to the number of unfavorable
outcomes. To find the odds against it, we reverse the order of these two numbers.
If an event has a probability of 30%, what are the odds in favor of it, and what are the odds against it? (Express your odds
lowest terms.)