Basic Math & Pre-Algebra All-in-One For Dummies (+ Chapter Quizzes Online)
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What’s the likelihood that the lottery ticket I bought will win?
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What’s the likelihood that my new car will need repairs before the warranty runs out?
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What’s the likelihood that more than 100 inches of snow will fall in Manchester, New Hampshire, this winter?
![image0.png](https://www.dummies.com/wp-content/uploads/216050.image0.png)
In this case, a favorable outcome is simply an outcome in which the event you’re examining does happen. In contrast, a possible outcome is an outcome that can happen.
For example, suppose you want to know the probability that a tossed coin will land heads up. Notice that there are two possible outcomes (heads or tails), but only one of these outcomes is favorable — the outcome in which heads comes up. To find the probability of this event, make a fraction as follows:
![image1.png](https://www.dummies.com/wp-content/uploads/216051.image1.png)
So the probability that the coin will land heads up is 1/2.
So what’s the probability that when you roll a die, the number 3 will land face up? To figure this one out, notice that there are six possible outcomes (1, 2, 3, 4, 5, or 6), but in only one of these does 3 land face up. To find the probability of this outcome, make a fraction as follows:
![image2.png](https://www.dummies.com/wp-content/uploads/216052.image2.png)
So the probability that the number 3 will land face up is 1/6.
And what’s the probability that if you pick a card at random from a deck, it’ll be an ace? To figure this out, notice that there are 52 possible outcomes (one for each card in the deck), but in only four of these do you pick an ace. So
![image3.png](https://www.dummies.com/wp-content/uploads/216053.image3.png)
So the probability that you’ll pick an ace is 4/52, which reduces to 1/13.
Probability is always a fraction or decimal from 0 to 1. When the probability of an outcome is 0, the outcome is impossible. When the probability of an outcome is 1, the outcome is certain.