学校鼓励学生参加社会实践，小明和他的同学利用寒假一周时间对市公交10路车起点站的一周乘车人次进行了统计，以每天800人次为准，超过的人次记为正数，不足的人次记为负数．记录一周情况如下：

（1）求该起点站在这一周内平均每天乘客的人次，并估计一下2005年6月份（30天）该起点站乘客的总人次；

（2）若将2005年6月份该起点站每天乘客人次整理后，按人次由小到大排列，分成五组，且每组的频率之比依次为1：2：1：3：3，请你说明这个月该起点站乘客人次的中位数能否落在某个小组内．

下列物质属于纯净物的是（　　）

    My dad works from Monday to Friday in a bank. He uses the computer to count money. His job is very important in the bank.

    Dad is also busy at home. At weekends he cooks dinner. Usually he cooks Italian food. On Sundays he makes five pieces of pizza. Sometimes he cooks chicken and makes Chinese food. My mum watches and helps him. I help my dad, too. I wash the dishes.

    Many people think it is strange for a man to cook. But my dad enjoys his hobby. Cooking relaxes him. He is a weekend cook.