In Wellington, a city of 360,000 citizens, there has been an outbreak of vampires and werewolves There are 3,000 people infected
with vampirism and 21,000 people infected with werewolfism. The number of people infected with both vampireism and warewolfism is 600. Calculate the probability that someone has vampireism given that they have has werewolfism.
The total number of people that have werewolfism is 21,000.
Of those 21,000, 600 also have vampirism, while the remaining 20,400 do not. Therefore, the probability that someone has vampirism, given that they have werewolfism is:
