A certain school has an enrollment of 400 students.Must there be at least two students in this school whose birthdays fall on the same day of the year?For this problem consider only non leap years.
Not at all. It could happen that all 400 students have the same birthday.
However, since there are only 365 days in a year, if we stipulate that no more than 35 students (or some smaller number) have the same birthday, then yes, some day must be duplicated.