Question

【題目】電腦鍵盤上的字母為何不按順序排列？請你來做一項統計，下面是一篇小短文，根據短文中字母a，b出現的機會完成后面提出的問題：
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．
根據上文填表

出現字母的個數	100	150	200	250	300	350	400
出現字母a的頻數
出現字母a的頻率
出現字母b的頻數
出現字母b的頻率

Answer 1

【答案】解：如圖所示：

出現字母的個數	100	150	200	250	300	350	400
出現字母a的頻數	12	18	23	28	36	38	45
出現字母a的頻率	0.12	0.12	0.115	0.112	0.12	0.109	0.113
出現字母b的頻數	3	3	4	4	6	6	6
出現字母b的頻率	0.03	0.02	0.02	0.018	0.02	0.017	0.015

【解析】根據頻數的概念及頻率的計算方法：頻率=求解．
【考點精析】掌握頻數與頻率是解答本題的根本，需要知道落在各個小組內的數據的個數為頻數；每一小組的頻數與數據總數（樣本容量n）的比值叫做這一小組的頻率．