Question

Question 7 0/2 pts This table is based on records of "injury" motor vehicle accidents where the occupants either sustained a nonfatal injury or at least one of the occupants sustained a fatal injury. The data were compiled by a State Highway Safety and Motor Vehicles Office. If we randomly select someone injured in a motor vehicle accident, what is the probability that person was wearing a seatbelt and was not fatally injured? Enter your answer as a decimal and round to four decimal places. Nonfatal Injury Fatal Injury Row Total Seat belt 412,364 518 412,882 No seat belt 162,427 1,694 164,121 Column total 574,791 2,212 577,003 0.7174

Answer 1

7. Probability = 412364/577003 = 0.7147 (ans)

8.

X follows a Normal distribution with mean = 1.25 and S.D = 0.08 Then z=(x-mean)/SD = (x-1.25)/0.08 follows standard Normal. We need to find x such that P(X< x)= 0.9 =z= 1.28 [Using Normal table or Excel formula NORM.S.INV(0.9)] = (x-1.25)/0.08 = 1.28 =x= 0.08*(1.28)+1.25 = 1.35

9.

npo (1– Po)210 >nx0.07x(1–0.07) 10 =n2153.61 = 154 (ans)