If the prob. that I will be alive in 15 years is 0.7 and....

If the probability that I will be alive in 15 years is 0.7 and the probability that you will be alive in 15 years is 0.9, what is the probability that neither of us is alive in 15 years?

I found that the probability that they are both alive is .63. How would I go about finding neither?

probability I am alive P=.7
prob. I died Q=.3

prob you are alive p=.9
prob you died q=.1

prob both alive=Pp=[.7][.9] = .63
prob both dead = Qq=[.3][.1]=.03
prob I am alive and you dead = Pq=[.7].1=.07
prob I am dead and you alive= [.3][.9]=.27

total of course =1
Arthur

Thank you~

Thank you, that answer just seemed to easy when I got it!

Your welcome
remember:
P is probability you are alive,then Q is probability you are dead
P+Q=1

p is probability I am alive , the q is probability I am dead
p+q=1

1=[P+Q][p+q]
1=Pp+Pq+pQ+qq all four cases

Arthur