(3) Let's pretend that the probability of living to age 70 is 0.63 and the probability of living to age 80 is 0.24. If a person reaches their 70th birthday, what is the probability that they will live to age 80? (4) In January, the train from New York to Boston arrives on schedule 80% of the time. When it snows in Boston, however, the train arrives on schedule only 65% of the time. On any given January day in Boston, assume that there is a 25% chance of snow. If the train arrives on schedule in Boston during January, what is the probability that it snowed?