In part (a) of Exercise 13, leap years were ignored in finding the probability that a randomly selected person will have a birthday on October 18.
a. Recalculate this probability, assuming that a leap year occurs every 4 years. (Express your answer as an exact fraction.)
b. Leap years occur in years evenly divisible by 4, except they are skipped in 3 of every 4 centesimal years (years ending in 00). The years 1700, 1800, and 1900 were not leap years, but 2000 was a leap year. Find the exact probability for this case, and express it as a fraction.