PROBABILITY
To answer a probability question, you need to know not only how to use the general probability
formula, but also how to deal with multiple probabilities and probabilities that events will not
occur. You have a little bit of everything in Example 9.
Example 9
It’s unlikely that a probability question on Math 2 will hinge only on applying the basic probability
formula. Instead, a question is much more likely to call on you to figure out the probability of two
independent events, or to determine the likelihood that an event will not occur by subtracting the
probability that it will occur from 1. In this example, you’re asked to figure the probability of an
event that could occur in more than one way. To do so, follow four simple steps.
PROBABILITY FORMULAS
If the probability that an event will occur is a, then the probability that the event will not
occur is 1 – a.
Two fair dice are tossed simultaneously. What is the probability that the product of the numbers
that land showing is at least 25?