- #1

kthouz

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95% of car drivers wear seatbelt, 64% of car drivers involved in serious accident die if not wearing seatbelt whereas 12% of those that do wear a seatbelt die. Calculate, correct to 3 significant figures, the percentage of drivers who died and were not wearing seatbelts.

Let A= “wear seatbelt”; B= die; A’= don’t wear seatbelt.

P(A)= 95%

P(A’)=100%-95%=5%

P(B/A’)=64%

P(B and A’)=?

By formula of conditional probability P(B/A’)= [P(B and A’)]/[P(A’)]

Then P(B and A’)= [P(B/A’)]*[P(A’)]

P(B and A’)= 0.64*0.05=0.032=3.20%