From the regression results you obtain in part (2b), determine if each of the explanatory variables used in the regression is statistically significant at a 5 percent level (This means 2.5 percent in each tail of the distribution). You will need to use the t distribution table for this purpose. In your answer, make sure you state what the critical value of t is for each independent variable. The critical value is the value of t, such that if the t statistic for your independent variable ( from your Excel output) is greater than the critical t or less than (-1) times the critical t, then you reject the null hypothesis. Hint: To determine the critical t, you wil l need both the level of significance (2.5% in this case) and the degrees of freedom. You wi ll need to calculate the degrees ofeedom, which is the number of observations minus the number of independent variables minus 1. Degrees of freedom = NkI. (10 points} Given 28 observations in the data and 4 independent variables, the degrees of freedom necessary to calculate the critical tvalue equal 28-4-1 : 23. Using the provided t distribution table, the critical value t at 23 degrees of freedom at the 2.5% significance level (for a 95% confidence level hypothesis test) is 2.66866 for each of the 4 independent variables. Looking at the computed t-statistics for each variable, 'Month' is the only variable that is not statistically significant. Because -0.8713 is less than the critical value of 2.06866, we cannot reject the null hypothesis that the month coefficient