Re: [商管] [統計]-幾題觀念題

[vity (拉麵愛吃辣椒)]

※ 引述《ingles (transparent)》之銘言：
: 1. A recent article in the paper claims that business ethics are at an
:    all—time low. Reporting on a recent sample, the paper claims that 41% of
:    all employees believe their company president possesses low ethical
:    standards.Suppose 20 of a company's employees are randomly and independently
:    sampled and asked if they thought their company president had low ethical
:    standards and their years of experience at the company.
:    Could the probability distribution for the number of years of experience be
:    modelled by binomial probability distribution?
:    (A) No, the employees would not be considered independent in the present
:        sample.
:    (B) Yes, the sample size is n = 20.
:    (C) No, a binomial distribution requires only two possible outcomes for each
:        experimental unit sampled.
:    (D) Yes, the sample is a random and independent sample.
我會選C 因為他實驗時問了1.想法和2.工作年資
不符合二項分配只有兩個出象的定義

A選項：題目告知隨機抽取 因此每次實驗應該是獨立
B    : 若n是20 那p的值(年資比例)題目並沒有給 不構成二項
D    ：隨機且獨立的條件 還無法構成二項

: 2.The registrar's office at State University would like to estimate the average
:   commute time and determine a 95% confidence interval for the average commute
:   time of evening university students from their usual starting point to campus.
:   A member of the staff randomly chooses a parking lot and selects the first
:   100 evening students who park in the chosen lot starting at 5:00 p.m.
:   The confidence interval is:
:   (A) not meaningful because the sampling distribution of the sample mean is
:       not normal.
:   (B) meaningful because the sample size exceeds 30 and the central limit
:       theorem ensures normailty of the sampling distribution of the sample mean
:   (C) not meaningful because of the Tack of random. sampling.
:   (D) meaningful because the sample is representative of the population.

我會選B
由於CLT 使得CI有意義

A:大樣本的抽樣分配 可逼近常態
C：也很像對  並無詳述如何隨機抽取  但題目有說"隨機"選了一個停車亭
D：樣本要代表母體 再附加一些條件較合適

:   麻煩板上強者提供你們的看法~謝謝囉^^

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推 ingles:感謝v大熱心回答^^ 第一題我也是選(C),第二題我覺得(B)這個
→ ingles:選項感覺看似沒錯,可是題目沒告知是否為常態,是不是要先確
→ ingles:定為常態，才能使用CLT做近似?!
→ ingles:所以我這題是選(D)...雖然這個選項感覺也沒很好XD
推 qa77330:如果是常態　那幹嘛要近似
推 ayabf:峉 CLT就是說當樣本大時會趨近常態...
→ ingles:對吼~我這問題應該可以PO到笨版了~腦筋打結了我 = =a