There is a woman that has a 40% chance of being in Casper recently, a 30% chance of being in Denver and a 27% chance that she has been to both. Find the probablility that she has been to Casper if she has been to Denver.

C=Casper

D=Denver
Conditional probability:
P(C)=0.4
P(D)=0.3
P(C∪D)=0.27
Probability of having been to Casper given she has gone to Denver
=P(C|D)=P(C∪D)/P(D)
=0.27/P(0.3)
=0.9