题目

People often come across the word “SOHO” in the newspaper or magazine. But not everyone knows what it means(意思是). Actually “SOHO” means “small office home office”. Now many people use computers, so it is possible(可能的) for them to work at their homes. They needn’t go to offices. They can usually work faster and better at home. By working at home, they save(节省) a lot of time and energy. They needn’t spend time on the road and they won’t feel tired or angry because of the bad traffic. Maybe in the future, more and more people will be “SOHO” workers. (某学校研究性学习小组调查学生使用智能手机对学习成绩的影响，询问了30名同学，得到如下的列联表：使用智能手机不使用智能手机总计学习成绩优秀4812学习成绩不优秀16218总计201030（Ⅰ）根据以上列联表判断，能否在犯错误的概率不超过0.005的前提下认为使用智能手机对学习成绩有影响？（Ⅱ）从使用智能手机的20名同学中，按分层抽样的方法选出5名同学，求所抽取的5名同学中“学习成绩优秀”和“学习成绩不优秀”的人数；（Ⅲ）从问题（Ⅱ）中被抽取的5名同学，再随机抽取3名同学，试求抽取3名同学中恰有2名同学为“学习成绩不优秀”的概率.参考公式：，其中参考数据：0.050.0250.0100.0050.0013.8415.0246.6357.87910.828