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tonytony15 2017-10-29 01:29 PM

統計~ 我無基礎但要做

[img]https://i.imgur.com/8QZQvos.jpg[/img]

除咗a計到係0.09 之外我真係唔識, 請問點做??

[[i] 本帖最後由 tonytony15 於 2017-10-29 02:47 PM 編輯 [/i]]

Funjoe@852 2017-10-30 07:51 AM

[quote]原帖由 [i]tonytony15[/i] 於 2017-10-29 01:29 PM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=470084671&ptid=27023279][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]
https://i.imgur.com/8QZQvos.jpg

除咗a計到係0.09 之外我真係唔識, 請問點做?? [/quote]
B) use formula: E(x)=sum(x times P(x)) = expectation
Variance = E(x^2)-(E(x))^2
Standard deviation = sqrt(variance)

c) she needs at least 6 jobs to get 15K income, so the question asks for probabilty that she has 6 jobs or more.

D) translate the number of jobs into Income and calculate using formula in B above
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