[商管] 台大92商研統計

[CMD (QQ)]

由於小弟手邊的解答是高點 但年份悠久 有些題目打錯 板上文章也少

詳解有些也跟我想的不同 因此想上來問問各位先進

92 台大商研統計題目 http://www.lib.ntu.edu.tw/exam/graduate/92/92411.pdf


16.Suppose a committee of 3 people is to be selected from a group consisiting

of 4 men and 5 women. What is the probability that all three people selected

are men?  A)0.11 B)0.33 C)0.50 D)0.80

這題我算出來是0.04多  是不是題目有錯?


25.Let X1 and X2 be observations of a random sample from a distribution with

p.d.f. f(x)= 2x 0 < x < 1 , zero elsewhere. Evaluate the conditional

probability Pr( X1 < X2 | X1 < 2 X2).

A)3/8 B)8/17 C)4/7 D)3/11

這題我之前好像遇過 我算是1/4

但看解答還是不太了解為什麼分母的地方是先對x2積分

而不能上下分子分母都先對x1積分呢?  是不是範圍的定義問題?


39. In performing a regression analysis involving two numerical variables

(Y is dependent variable and X is independent variable), we are assuming

A) the variance of X and Y are equal

B) the variation around the line of regression is the same for each X value

C) that X and Y are independent

D) All of the above

我選A 答案是B  解答是說f(Y|X)的條件變異數相等 (?)


44. Which of the followings is correct?

A) the sample size in each independent sample must be the same if we are to

test for differences between the means of 2 independent populations

B) When we test for differences between the means of2 independent populations,

we can only use a two-tailed test

C) When testing for differences between the means of 2 related populations ,

we can use either a one-tailed or two-tailed test

D) The F distribution is symmetric.

我選B 答案是C  我選B是因為題目沒說是ANOVA 還是 t-test 所以我選B


煩請各位先進幫忙解惑  謝謝!! :)

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推 psdc258:第一題我算1/21，應是答案有誤
→ psdc258:第二題4/7，因雙重積分為線到線→點到點(就像你說的範圍定
→ psdc258:義問題)，且不可利用面積比較是因聯合機率分配不為常數
→ psdc258:第三題因自變項X為固定常數，代入之誤差項符合同質性
→ psdc258:第四題，ANOVA是用來驗證三個以上常態母體
→ psdc258:用推文是因為沒有很確定XD 我也是考生Q__Q
→ CMD:謝謝您的回答:) 不過ANOVA也可以用來驗證兩個母體吧?
→ CMD:只是ANOVA只能用雙尾 但t可用單尾 不過t^2 = F