问题如下图：
选项：
A. 
B. 
C. 
解释：
老师请问我们背诵的95%的区间不是1.96吗？难道是双尾是1.96，而单尾就是按10%来算就是1.65？是这个意思吗？不好意思复习冲刺的时候突然发现这个知识点掌握很差。
星星_品职助教 · 2019年11月26日
同学你好，
回忆下背诵这几组数字的背景，是在讲置信区间的时候给出的。由于这是一个分布里居中的“区间”的概念，所以95%的区间意味着左右有两个尾巴，面积一共是5%。也就是单侧面积2.5%。所以1.96实际上是单侧面积2.5%的关键值。（前提是正态分布）。
所以1.96可以应用于两个场合 1. 对应5%的双尾 2. 对应2.5%的单尾。
而这道题的题干中说的是“....greater than 26%”，所以不可能是双尾的情况。双尾的情况会说均值=26%。
同理，1.65对应的是90%的置信区间，也就是单尾的5%，或者双尾的10%。
考试的时候看题干分清楚单双尾即可，加油。
bodane · 2019年11月26日
1.65对应的是90%的置信区间，也就是单尾的5%，或者双尾的10%。？
bodane · 2019年11月27日
已明白了
NO.PZ2015120604000147 问题如下 Here is a table scribing sample statistifrom two bon' rate of return whiare both normally stributeover the past cas. If investor is consiring whether the meof bonB is greater th26%,whiof the following conclusion is least appropriate (significant level=5%) ? A.It is appropriate to use the Z-test. B.The meof bonB is not significant greater th26%. C.It is a one-tailetest. B is correct.It is appropraite to ues the one-taileZ-test because the sample size of bonB is bigger th30.The null hypothesis is: H0: μ ≤ 26%The test statistiα= 5% incates the criticvalue is equto ±1.65. Because 1.91 1.65, therefore, we shoulrejethe null hypothesis. 怎么确定原假设方向是小于？根据是否大于，怎么确定原假设和备择假设，，怎么分析
NO.PZ2015120604000147 问题如下 Here is a table scribing sample statistifrom two bon' rate of return whiare both normally stributeover the past cas. If investor is consiring whether the meof bonB is greater th26%,whiof the following conclusion is least appropriate (significant level=5%) ? A.It is appropriate to use the Z-test. B.The meof bonB is not significant greater th26%. C.It is a one-tailetest. B is correct.It is appropraite to ues the one-taileZ-test because the sample size of bonB is bigger th30.The null hypothesis is: H0: μ ≤ 26%The test statistiα= 5% incates the criticvalue is equto ±1.65. Because 1.91 1.65, therefore, we shoulrejethe null hypothesis.
NO.PZ2015120604000147 问题如下 Here is a table scribing sample statistifrom two bon' rate of return whiare both normally stributeover the past cas. If investor is consiring whether the meof bonB is greater th26%,whiof the following conclusion is least appropriate (significant level=5%) ? A.It is appropriate to use the Z-test. B.The meof bonB is not significant greater th26%. C.It is a one-tailetest. B is correct.It is appropraite to ues the one-taileZ-test because the sample size of bonB is bigger th30.The null hypothesis is: H0: μ ≤ 26%The test statistiα= 5% incates the criticvalue is equto ±1.65. Because 1.91 1.65, therefore, we shoulrejethe null hypothesis. 当落在阴影的时候，rejeH0，接受Ha,则表达为is significantily fferent from H0么？
NO.PZ2015120604000147问题如下Here is a table scribing sample statistifrom two bon' rate of return whiare both normally stributeover the past cas. If investor is consiring whether the meof bonB is greater th26%,whiof the following conclusion is least appropriate (significant level=5%) ?A.It is appropriate to use the Z-test.B.The meof bonB is not significant greater th26%.C.It is a one-tailetest. B is correct.It is appropraite to ues the one-taileZ-test because the sample size of bonB is bigger th30.The null hypothesis is: H0: μ ≤ 26%The test statistiα= 5% incates the criticvalue is equto ±1.65. Because 1.91 1.65, therefore, we shoulrejethe null hypothesis. 请问对于这道题大样本的情况，计算出来t统计量后查对应的5%的criticvalue是不是既可以查z分布表也可以查t分布表
NO.PZ2015120604000147 问题如下 Here is a table scribing sample statistifrom two bon' rate of return whiare both normally stributeover the past cas. If investor is consiring whether the meof bonB is greater th26%,whiof the following conclusion is least appropriate (significant level=5%) ? A.It is appropriate to use the Z-test. B.The meof bonB is not significant greater th26%. C.It is a one-tailetest. B is correct.It is appropraite to ues the one-taileZ-test because the sample size of bonB is bigger th30.The null hypothesis is: H0: μ ≤ 26%The test statistiα= 5% incates the criticvalue is equto ±1.65. Because 1.91 1.65, therefore, we shoulrejethe null hypothesis. 原假设是≤，那么难道不应该看左尾吗？即检验统计量1.91和criticvalue中-1.65比，这样落在接受域。