Mothers Against Drunk Driving MADD is a very visible group w

Mothers Against Drunk Driving (MADD) is a very visible group whose main focus is to educate the public about the harm caused by drunk drivers. A study was recently done that emphasized the problem we all face with drinking and driving. Five hundred accidents that occurred on a Saturday night were analyzed. Two items noted were the number of vehicles involved and whether alcohol played a role in the accident. The numbers are shown below:

                                                            Number of Vehicles Involved

Did alcohol play a role?

1

2

3

Yes

60

110

30

200

No

40

215

45

300

100

325

75

Given that alcohol was not involved, what proportion of the accidents involved a single vehicle?

Solution

The proportion of the accidents involved a single vehicle is

P(single vehicle | alcohol was not involved)

=P(single vehicle and alcohol was not involved) / P(alcohol was not involved)

=40/300

=0.1333