题目

Visit the skywalk at Grand Canyon West Today!   For Booking Call:1-866-944-7236   Package Fee:   $289 Per Adult;  $274 Per Child．   All Fee’s Included．NO Hidden Cost．Experience the newly opened Grand Canyon（大峡谷）West Skywalk in Colorado．Departing from Grand Canyon’s South Rim by Airplane to Grand Canyon’s West Rim, you will land and take a ground tour to the Skywalk! Walk on air for 70 feet over the edge of Grand Canyon West． This Skywalk has been open since March 28,2007．Daily visitorship to the Skywalk has been over 4,000 people．Please be patient to enjoy yo15．某大学高等数学这学期分别用A，B两种不同的数学方式试验甲、乙两个大一新班（人数均为60人，入学数学平均分和优秀率都相同；勤奋程度和自觉性都一样）．现随机抽取甲、乙两班各20名的高等数学期末考试成绩，得到茎叶图：     甲班乙班合计优秀   不优秀   合计   （1）学校规定：成绩不得低于85分的为优秀，请填写下面的2×2列联表，并判断“能否在犯错误率的概率不超过0.025的前提下认为成绩优异与教学方式有关？”下面临界值表仅供参考：P（k2≥k）0.150.100.050.0250.0100.0050.001k2.0722.7063.8415.0246.6357.87910.828（参考方式：${k^2}=\frac{{n{{（{ad-bc}）}^2}}}{{（{a+b}）（{c+d}）（{a+c}）（{b+d}）}}$，其中n=a+b+c+d）（2）现从甲班高等数学成绩不得低于80分的同学中随机抽取两名同学，求成绩为86分的同学至少有一个被抽中的概率．