Question

Do seat belts save lives? A public health researcher conducted a cross-sectional study of fatality outcomes and seat belt use of 100 victims of motor vehicle accidents in a large city over the course of one month. There were a total of 30 deaths. Of the 100 victims, 50 wore seat belts. Of those victims who wore seat belts, 10 died. What is the probability that a victim randomly selected from this group was alive, given that they did not wear a seat belt?

a. 0.2

b. 0.4

c. 0.6

d. 0.7

e. 0.8

Answer 1

Solution: Option ( c ) = 0.6

total number of victims = 100

total number of deaths = 30

number of victims who wore seat belt = 50

number of deaths who wore seat belts = 10

number of victims died who did not wear seat belt = 50

number of deaths who did not wear seat belts = 30 - 10 = 20

number of victims alive who did not wear seat belts = 50 - 20 = 30

probability that a victim randomly selected from this group was alive, given that they did not wear a seat belt = ( number of victims alive who did not wear seat belts  / number of victims died who did not wear seat belt )

= 30 / 50

= 0.6