问题如下图：
选项：
A. 
B. 
C. 
解释：
不是“总体方差已知用Z，总体方差未知用T，吗？为什么这道题用Z分布是正确的？
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. 单尾的5% α 是1.65，双尾是1.96 对吗老师
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
