b) What is the total number of days with 0, 1, 2 or 3 absentees? So the remaining days (of the 100 observed) had more than 3 absentees. The required probability is this latter number of days divided by 100.
c) Add up the number of days that had the specified number of absentees (0, 1 or 2 absentees) and divide by 100.
CB