For example a school superintendent wishes to determine the proportion of children in a large school system who come to scho6l without breakfast have been vaccinated for flu.

• 例如一个学校的主管(负责人)希望可以在一个庞大的学校体系中确定没有吃早餐就来上课的孩子（学生）接受流感预防接种的人数比例。