If the teacher picked a specific day (say, 16 September), then the chance that at least one student was born on that specific day is 1 − ( 364 / 365 ) 30 {\displaystyle 1-(364/365)^{30}} , about 7.9%.
若老师选择特定日期（例如9月16日），则至少有一名学生在那天出生的概率是 1 − ( 364 / 365 ) 30 {\displaystyle 1-(364/365)^{30}} ，约为7.9%。