Question 179359
The probability is 1 in 4,000,000 that a single auto trip in the United States will result in a fatality. Over a lifetime, an average U.S. driver takes 50,000 trips. 
(a) What is the probability of a fatal accident over a lifetime? Explain your reasoning carefully. Hint: Assume independent events.
Ans: [4/10^6]^50,000
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Why might the assumption of independence be violated?
Some folks are more prone to accidents than others.  The probability 
probably changes from adolescence thru adulthood thru senility.
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(b) Why might a driver be tempted not to use a seat belt “just on this trip”
The probability of an accident on any given trip is very low.
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Cheers,
Stan H.