Question

【題目】電腦鍵盤(pán)上的字母為何不按順序排列？請(qǐng)你來(lái)做一項(xiàng)統(tǒng)計(jì)，下面是一篇小短文，根據(jù)短文中字母a，b出現(xiàn)的機(jī)會(huì)完成后面提出的問(wèn)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(jù)上文填表

出現(xiàn)字母的個(gè)數(shù)	100	150	200	250	300	350	400
出現(xiàn)字母a的頻數(shù)
出現(xiàn)字母a的頻率
出現(xiàn)字母b的頻數(shù)
出現(xiàn)字母b的頻率

Answer 1

【答案】解：如圖所示：

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

【解析】根據(jù)頻數(shù)的概念及頻率的計(jì)算方法：頻率=求解．
【考點(diǎn)精析】掌握頻數(shù)與頻率是解答本題的根本，需要知道落在各個(gè)小組內(nèi)的數(shù)據(jù)的個(gè)數(shù)為頻數(shù)；每一小組的頻數(shù)與數(shù)據(jù)總數(shù)（樣本容量n）的比值叫做這一小組的頻率．