虽然做对了，但是不理解

NO.PZ2018062016000140问题如下ring the table below, the memonthly return of X Inx in the first five years have been fferent ththe mereturn in the seconfive years.Let the μ1 stanfor the population mereturn for the year1 through ye5 anμ2 stanfor the population mereturn for the ye6 through ye10, the following hypothese: H0: μ1 – μ2 = 0 versus Hμ1 – μ2 ≠ 0 Assume ththe significant level is 0.05Whiof the following options is most accurate?A.The null hypothesis will rejecteif t -1.98 or t 1.98. B.The t-test h119 grees of freem. C.The rejection points are ±1.658.A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t -1.980 or t 1.980.谢谢谢。。。。。。。

NO.PZ2018062016000140 问题如下 ring the table below, the memonthly return of X Inx in the first five years have been fferent ththe mereturn in the seconfive years.Let the μ1 stanfor the population mereturn for the year1 through ye5 anμ2 stanfor the population mereturn for the ye6 through ye10, the following hypothese: H0: μ1 – μ2 = 0 versus Hμ1 – μ2 ≠ 0 Assume ththe significant level is 0.05Whiof the following options is most accurate? A.The null hypothesis will rejecteif t -1.98 or t 1.98. B.The t-test h119 grees of freem. C.The rejection points are ±1.658. A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t -1.980 or t 1.980. 由于拒绝原假设的原则为|t-statistic|＞|criticvalue|，可知A正确。請問|t-statistic|為多少？這題如何計算，謝謝，

NO.PZ2018062016000140问题如下ring the table below, the memonthly return of X Inx in the first five years have been fferent ththe mereturn in the seconfive years.Let the μ1 stanfor the population mereturn for the year1 through ye5 anμ2 stanfor the population mereturn for the ye6 through ye10, the following hypothese: H0: μ1 – μ2 = 0 versus Hμ1 – μ2 ≠ 0 Assume ththe significant level is 0.05Whiof the following options is most accurate?A.The null hypothesis will rejecteif t -1.98 or t 1.98. B.The t-test h119 grees of freem. C.The rejection points are ±1.658.A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t -1.980 or t 1.980.可以詳細講一下做題思路嗎

NO.PZ2018062016000140 The t-test h119 grees of freem. The rejection points are ±1.658. A is correct. The two samples are awn from two fferent time perio, so they are inpennt samples. The population variances cassumeto equal. Unr all consirations, the t-test h60+60-2=118 grees of freem.For a two-tailetest, the significant level of 0.05, the rejection points are ±1.980, so we will rejethe null if t1.980. 为什么是T分布不是Z分布呢 从题干哪里可以判断哇