The probability that a vehicle entering the Luray Caverns has Canadian license plates is 0.12; the probability that it is a camper is 0.28; and the probability that it is a camper with Canadian license plates is 0.09. What is the probability that a camper entering the Luray caverns has Canadian license plates? At first I thought that it was (0.12)(0.28) but I was wrong. Any comments?

Question

a_clan · Answer

I think it is just 0.12
We do not have to factor in the probability for it being a camper because it is already given that it is a camper. So, the probability that it is a camper is 1.

anonymous · Answer

In the book it was 9/28 but I do not know why...

anonymous · Answer

we are looking for the intersection so let C stand for camper and P for Canadian plate 
so p(PintersectionC)=p (C/P)/p (C)
now substitute 9/28=.3214285714