Question

1. Mothers Against Drunk Driving 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. Four 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:
   
   
   
   
   Referring to Table 4-1, given that 3 vehicles were involved, what proportion of accidents involved alcohol?

   		20/50 or 40%
   		20/170 or 11.77%
   		20/400 or 5%
   		20/30 or 66.67%

Answer 1

P(accidents involved alcohol | 3 vehicles were involved) = Number of cases in which alcohol was involved and accidents involved 3 vehicles / Number of accidents that involed 3 vehicles

= 20/50

= 0.4

= 40%

20/50 or 40%