问题如下：
In one multiple regression, there are seven independent variables. The sum of squared residuals is 4725 and the total sum of squares is 9880. In addition, there're 70 observations in the sample.
The critical F- value for testing H0 : B1 = B2 = B3 = B4 =B5 =B6 =B7 = 0 vs. HA: at least one Bj ≠ 0 at the 5% significance level is closest to:
选项：
A.F(6,63)
B.F(7,62)
C.F(6,64)
D.F(7,63)
解释：
B is correct.
考点：Hypothesis Test and Linear Regression with Multiple Regressors
解析：1、因为是联合检验H0=B1=B2=...=0，所以用F-test。
2、F-test的自由度是一对数字：前一个数字，因为seven independent variables (k)，所以是7，后一个数字＝n-k-1=70-7-1=62 （70 observation, 7 independent variable).
3、最后去查F(7,62)，也就是B选项（只需要你判断出要求的是F(7,62)，之后就可以查表了。考试时是给你几个F(a,b)的值，让你选）
F检验查什么表啊？考试是不是只给Z表？7，62 怎么查z表啊？
