化简与求值：

（1）化简：$\frac{1+\tan 15°}{1-\tan 15°}$；

（2）已知α，β都是锐角，cosα=$\frac{1}{7}$，cos（α+β）=﹣$\frac{11}{14}$，求cosβ的值．

      What do you usually do to get pocket money from your parents? In western countries, many children do chores to get pocket money. They usually start to do this at 10 years old.
School students have to do homework and study for tests. They don't have a lot of free time in the week. They often do chores at the weekend.
       Young kids only do easy chores. So they don't get much money. But that's all right. Many of them only want to buy candy. And candy is cheap! They help wash up after dinner and feed the family cat or dog.
When they get older, kids want to buy more and more things. They want things that are more expensive than candy. Then they have to work harder! They often wash the family car, cut the grass, walk the dog and cook dinner.
Some jobs are a good way for kids to learn new things. For example, they can learn to use a lawnmower(割草机) or how to cook. Of course, their parents help them at first.

（Ⅰ）若依据去掉一个最高分和一个最低分规则计算应聘老师成绩，试确定最终应聘成功的2名数学老师的序号；

（Ⅱ）在课堂实录环节，每名应聘老师都需要从5名评审专家中随机选取2名进行点评，且每名应聘老师的选择互不影响，设X表示评审专家A进行点评的次数，求X的分布列以及数学期望；

（Ⅲ）记评审专家A与评审专家B给出的评分的方差分别为 $S_1^2，S_2^2$ ，试比较 $S_1^2$ 与 $S_2^2$ 的大小．（只需写出结论）

Mo Yan is a great____(作家)in the world.