Probability ideas for today:
If the probability of something happening is measured by the number P, then the probability of it not happening is 1-P
The probability of two things both happening is less than the probability of just one of the things happening, and you get that probability for both by multiplying the probabilities of them happening separately. Choosing two things out of a group is easiest to analyze by multiplying.
Good sources for probability info:
Your textbook, section 7.2
The Math Goodies sections on probability
Practice problems
1. The weatherman says that there is a 40% chance of rain tomorrow. What is the probability that it will not rain tomorrow?
2. If I have a bag with 5 red and 3 blue marbles, and I pick two out (one and then the other,without replacing the first)