
Conditional Probability
The National Highway Traffic Safety Administration is interested in the effect of seat belt use on saving lives. The following table shows a report on children under the age of 5 who did not wear seat belts and were involved in motor vehicle accidents in which at least one fatality occurred between 1985 and 1989.
Ages Survivors Fatalities Age % in Report
0 45% 55% 14%
1 64% 36% 16%
2 71% 29% 23%
3 75% 25% 22%
4 77% 23% 25%
Find the conditional probability that a child is 3 years old given that he survived in an accident.
My answer:
I set the problem up to be P(child is 3 years old  he survived in an accident).
That equals P(child is 3 years old and survived in an accident)/P(survived in an accident).
The numerator equals 0.75, but I am having trouble figuring out what the denominator is. How do I find P(survived in an accident)?