### 8.1 Assigning a Measure to Likelihood

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• Math Help

Note how the probabilities are given in Example 3. Instead of using a fraction, decimal, or percent, the annual risk of being killed in a plane crash is given as "about 1 in 11 million." This is a convenient way of writing a probability that some may find easier to understand than the other ways. For instance, consider these other ways of writing the probability 1 in 11 million.

• Fraction:
• Decimal: 0.000000091
• Percent: 0.0000091%
• Consumer Suggestion

Understanding the risks involved with riding and operating a motorcycle is a key component to motorcycle safety. To learn more about motorcycle laws, training, safety and risks, visit the Motorcycle Safety Foundation.

• Checkpoint Solution

Per 100 million passenger miles, there are about 31 motorcycle deaths, 2 plane deaths, 1.5 train deaths, and 1.5 automobile deaths. So, for the same number of miles traveled, the risk of death while riding a motorcycle is about times worse than the risk while flying in a plane and about times worse than the risk while riding in a train or automobile. For the same number of miles traveled, the risk of death while flying is about times worse than the risk while riding in a train or automobile. Travel by train and automobile have the same risk of death.

There are 2 deaths for every 100 million airplane miles flown. So, the risk of death from taking a 2000-mile plane flight is

or 0.004%. It is true that the more you fly, the more you increase the likelihood of an accident. Flying carries a certain risk of an accident. So, by flying multiple times, you take that risk over and over, increasing your overall likelihood of an accident.

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/ ____||  |  ___||     ___    /_   _// \ \\ / //
/ //---`'  | ||__      /   ||   -| ||-   \ \/ //
\ \\___    | ||__     | [] ||   _| ||_    \  //
\_____||  |_____||    \__ ||  /_____//    \//
`----`   `-----`      -|_||  `-----`      `
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Ron Larson (author)9 years ago |
I like David Ropeik's book "A Practical Guide for Deciding What’s Really Safe and What’s Really Dangerous in the World Around You". It does a good job in helping people understand the probabilities of risk.
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