Leap Years and Guessing Birthdays In part

(a) of Exercise 17, 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 four years.

(Express your answer as an exact fraction.)

b. Leap years occur in years evenly divisible by 4, except they are skipped in three of every four 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 an exact fraction.