Question 8: In a certain country, the probability that a woman reaches the age of 70 is 0.7 and the probability that a woman lives to be 80 is 0.5. (a) If a woman from that country is 70 years old, what is the conditional probability that she will survive to 80 years? (b) Suppose that three sisters born in that country live completely independent lives. What is the probability that they will all be alive at the age of 70? (c) If the three sisters are all alive at the age of 70, what is the probability that they will all be alive at the age of 80?