问题如下：
Ida Lee and his team collect a lot of analysis of statistical data about the car market .According to the data, they come to the conclusion that the mean price of SUV is more than $46,435 in his country. Then they randomly select 64 SUVs whose mean price is $46,760. Assuming the standard deviation of the sample is 1370. Ida Lee conducts a hypothesis test to check their conclusion. At which significant level should Ida Lee reject the null hypothesis?
选项：
A.0.5%.
B.5%.
C.1%.
解释：
B is correct.
If the significant level is 5%, the critical value=1.669<1.8978, Ida Lee should reject the null.
If the significant level is 0.5%, the critical value=2.656>1.8978, Ida Lee will fail to reject the null.
If the significant level is 1%, the critical value=2.387>1.8978, Ida Lee will fail to reject the null.
这道题我的思路，是先算出t critical value=(46760-46435)/(1370/8)=1.8978，单尾，根据significant level 给出三个数字0.5%对应2.58临界值，5%对应临界值1.65,1%对应临界值在1.96-2.58之间估计；而之前算出t critical value1.8978应该在临界值右边才会拒绝原假设，所以选对应5%？？
