To get the probability that two independent events will both occur, multiply
the individual probabilities. Thus, to get the probability that it will not rain
today or tomorrow, multiply 40% and 25%:
(40%)(25%) = (0.40)(0.25) = 0.10 = 10%
The answer is (A).
If you don’t already at least half-know these formulas, they’re probably not
worth worrying about. But if you can remember them without too much
trouble, one of them might come in handy on test day.
There’s a lot of material in this chapter, but remember that it’s just the tip of
the content pyramid. You can use the Miscellaneous Topics Follow-Up Test to
see how much you’ve picked up from this chapter, but keep it in perspective.
It’s a higher priority to master the material in the chapters preceding this one.
THINGS TO REMEMBER:
Rules of Imaginary Numbers