如图，反比例函数y=$\frac{k}{x}$（k＞0）与一次函数y=$\frac{1}{2}$x+b的图象相交于两点A（x₁，y₁），B（x₂，y₂），线段AB交y轴与C，当|x₁-x₂|=2且AC=2BC时，k、b的值分别为（   ）．

如图，有一圆柱体，底面周长为15cm，高AB=8cm，在圆柱的下底面A点处有一只蚂蚁，它想绕圆柱体侧面一周爬行到B点处，那么它们所行走得最短路程是（　　）

某中学高一年级的一研究性学习小组为了解本年级1300名学生每学期参加社会实践活动的时间，随机对该年级100名学生进行了调查，结果如下表：

（1）在这个统计中，众数是多少？中位数是多少？

（2）补全下面的频率分布表和频率分布直方图：

（3）请你估算这所学校该年级的学生中，每学期参加社会实践活动时间不少于9天的大约有多少人？

注意：1.每处错误及其修改均仅限一词；2.只允许修改10处，多者（从第11处起）不计分。

    The teenage year from 13 to 19 were the most difficult time for me. They were also the best and worse years in my life. At the first, I thought I knew everything but could make decisions by myself. Besides, my parents didn't seem to think so. They always tell me what to do and how to do it. At one time, I even felt my parents couldn't understand me so I hoped I could be freely from them. I showed them I was independent by wear strange clothes. Now I am leaving home for college. At last, I will be on their own, but I still want to have my parents to turn whenever I need help.