NO.PZ201709270100000107
问题如下：
7. The upper bound for the 95% confidence interval for the coefficient on the debt ratio in the regression is closest to:
选项：
A.−1.0199.
B.−0.3947.
C.1.4528.
解释：
B is correct.
The calculation for the confidence interval is −4.1589 ± (2.011 ×1.8718). The upper bound is −0.3947. The 2.011 is the critical t-value for the 5% level of significance (2.5% in one tail) for 48 degrees of freedom.
老师，我记得前面有一个类似的题目求置信区间，用的是mean加上t*standard error，就是用0.3979+t*standard error，为什么这里就直接用系数的估计值？
