Suppose you're analyzing a population of 100,000 people, and you're trying to understand life expectancy. Within this population of 100,000 people, 65% can expect to live to the age of 70, while 25% can expect to live to age 80. Given that a person is already 70, what is the probability that they live to the age 80?
Hint: think about conditional probability theory when solving this one.