题目内容
11、电脑键盘上的字母为何不按顺序排列？请你来做一项统计，下面是一篇小短文，根据短文中字母a，b出现的机会完成后面提出的问题：
Two Trips
Jack brought a small plane and began to fly it． He soon became excited and made his plane all kinds of tricks．
Jack had a friend，named Tom． One day Jack said to him，“I will pick you up in my plane．““I will be glad to．'answered Tom． They went up，and Jack flew around for half an hour and did all kinds of tricks in the air． Then they came down． Tom was to be back safely，and said to Jack，“Well，Jack，thank you very much for those two trips in your plane．“Jack was very surprised and asked，“Two trips？““Yes，my first and my last．'an-swered Tom．
（1）根据上文填表
Two Trips
Jack brought a small plane and began to fly it． He soon became excited and made his plane all kinds of tricks．
Jack had a friend，named Tom． One day Jack said to him，“I will pick you up in my plane．““I will be glad to．'answered Tom． They went up，and Jack flew around for half an hour and did all kinds of tricks in the air． Then they came down． Tom was to be back safely，and said to Jack，“Well，Jack，thank you very much for those two trips in your plane．“Jack was very surprised and asked，“Two trips？““Yes，my first and my last．'an-swered Tom．
（1）根据上文填表
分析：根据频数的概念及频率的计算方法：频率=$\frac{频数}{数据总数}$求解．
解答：解：如图所示：
点评：本题考查了频数的概念及频率的计算方法．
频数是指每个对象出现的次数．
频率是指每个对象出现的次数与总次数的比值（或者百分比）．即频率=$\frac{频数}{数据总数}$．
频数是指每个对象出现的次数．
频率是指每个对象出现的次数与总次数的比值（或者百分比）．即频率=$\frac{频数}{数据总数}$．
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