# Need help with probabilities

1. Oct 17, 2004

### dionys

Hi again...This is my last question for today.
I know that i send a lot of threads but...i dont have anyone else to help me.

Most of the times i dont send any solutions.I try but sometimes i dont understand and so...i dont have something to write.I post frequently
because if i dont give a 50% of correct answers i will not have the chance to write in the final exams...its a stupid rule.

My last 2 questions for today are.

1.We must prove that if P(A/B)=1 then P(B compl. / A compl.)=1
i wrote a lot of things but ..i didnt prove nothing : ~)

2.A and B are two events with non zero probabilities.
I must show (prove) if the following are i)correct,ii)faulse iii)correct under some conventions.
a)if A and B are foreign then they are independent (i dont know if this is the correct word) butif they are foreign P(A[intersect]B)=[empty-set]
b)if A and B are independent then they are foreign
c)P(A)=P(B)=0.6 A,B are foreign
c)P(A)=P(B)=0.6 A,B are independent

2. Oct 19, 2004

### TenaliRaman

for 1>
what is the basic definition of P(A/B) ??
(There is one in terms of intersections!)
once u have this, simply work through it....

for 2>
what u have done with this so far?

-- AI