问题如下图：
选项：
A. 
B. 
C. 
解释：
为什么是查T分布表呢？是因为总体方差未知吗？
星星_品职助教 · 2019年08月27日
同学你好，从题目本身来说，这道题题目中没有说是正态分布，同时总体方差未知，所以用了t分布。
从备考的角度来讲，对于练习题而言，很多题目的出题方式都类似这种，不会明确的告诉你用t还是用z。但用 t分布和z分布的结果几乎是不会有差别，因为t和z的critical value相差很小；就比如这道题，以5%为例，无论是用1.669还是1.645，最后结果都是一样的。
对于真实考试而言，用什么分布或者是用哪个critical value，题干会给出明确的信息，比较典型的一种形式就是告诉单尾5% significant level的critical value就按照1.65来计算。几乎不可能让考生自己去努力从题干中找信息去看到底用哪种分布。
而对于用哪种分布的考察方式，很大可能是直接出一个选择题，题干说方差未知，让考生选择用t还是用z。
加油
NO.PZ2015120604000137问题如下 I Lee anhis tecollea lot of analysis of statisticta about the cmarket .Accorng to the tthey come to the conclusion ththe mepriof SUV is more th$46,435 in his country. Then they ranmly sele64 SUVs whose mepriis $46,760. Assuming the stanrviation of the sample is 1370. I Lee concts a hypothesis test to chetheir conclusion. whisignificant level shoulI Lee rejethe null hypothesis?A.0.5%.B.5%.C.1%.B is correct.If the significant level is 5%, the criticvalue=1.669 1.8978, I Lee shoulrejethe null.If the significant level is 0.5%, the criticvalue=2.656 1.8978, I Lee will fail to rejethe null.If the significant level is 1%, the criticvalue=2.387 1.8978, I Lee will fail to rejethe null.老师可否展示下这个题的完整解题过程已经回答的答案感觉说的都是局部。谢谢
NO.PZ2015120604000137 问题如下 I Lee anhis tecollea lot of analysis of statisticta about the cmarket .Accorng to the tthey come to the conclusion ththe mepriof SUV is more th$46,435 in his country. Then they ranmly sele64 SUVs whose mepriis $46,760. Assuming the stanrviation of the sample is 1370. I Lee concts a hypothesis test to chetheir conclusion. whisignificant level shoulI Lee rejethe null hypothesis? A.0.5%. B.5%. C.1%. B is correct.If the significant level is 5%, the criticvalue=1.669 1.8978, I Lee shoulrejethe null.If the significant level is 0.5%, the criticvalue=2.656 1.8978, I Lee will fail to rejethe null.If the significant level is 1%, the criticvalue=2.387 1.8978, I Lee will fail to rejethe null. 请问此题需要记住t-test表的5%、1%、0.5%对应的数值吗？
NO.PZ2015120604000137问题如下 I Lee anhis tecollea lot of analysis of statisticta about the cmarket .Accorng to the tthey come to the conclusion ththe mepriof SUV is more th$46,435 in his country. Then they ranmly sele64 SUVs whose mepriis $46,760. Assuming the stanrviation of the sample is 1370. I Lee concts a hypothesis test to chetheir conclusion. whisignificant level shoulI Lee rejethe null hypothesis?A.0.5%.B.5%.C.1%.B is correct.If the significant level is 5%, the criticvalue=1.669 1.8978, I Lee shoulrejethe null.If the significant level is 0.5%, the criticvalue=2.656 1.8978, I Lee will fail to rejethe null.If the significant level is 1%, the criticvalue=2.387 1.8978, I Lee will fail to rejethe null.备择假设是小于，不应该是分布函数左侧面积，应该是小于关键值才才拒绝吗
NO.PZ2015120604000137 问题如下 I Lee anhis tecollea lot of analysis of statisticta about the cmarket .Accorng to the tthey come to the conclusion ththe mepriof SUV is more th$46,435 in his country. Then they ranmly sele64 SUVs whose mepriis $46,760. Assuming the stanrviation of the sample is 1370. I Lee concts a hypothesis test to chetheir conclusion. whisignificant level shoulI Lee rejethe null hypothesis? A.0.5%. B.5%. C.1%. B is correct.If the significant level is 5%, the criticvalue=1.669 1.8978, I Lee shoulrejethe null.If the significant level is 0.5%, the criticvalue=2.656 1.8978, I Lee will fail to rejethe null.If the significant level is 1%, the criticvalue=2.387 1.8978, I Lee will fail to rejethe null. 这是一个技术测试，谢谢。
NO.PZ2015120604000137 问题如下 I Lee anhis tecollea lot of analysis of statisticta about the cmarket .Accorng to the tthey come to the conclusion ththe mepriof SUV is more th$46,435 in his country. Then they ranmly sele64 SUVs whose mepriis $46,760. Assuming the stanrviation of the sample is 1370. I Lee concts a hypothesis test to chetheir conclusion. whisignificant level shoulI Lee rejethe null hypothesis? A.0.5%. B.5%. C.1%. B is correct.If the significant level is 5%, the criticvalue=1.669 1.8978, I Lee shoulrejethe null.If the significant level is 0.5%, the criticvalue=2.656 1.8978, I Lee will fail to rejethe null.If the significant level is 1%, the criticvalue=2.387 1.8978, I Lee will fail to rejethe null. 本题总体方差未知使用t检验，自由度是n-1，那计算标准误是使用n还是n-1