Suppose a researcher ran the following regression with the sample size of 300: COVID_i=_0 _1 Mask_i _i where the dependent variable is "Number of average daily COVID cases" in county i and the explanatory variable, Mask_i, is "Number of masks sold" in county i. The estimated equation is (COVID_i ) =200-0.5*Mask_i If there were 100 masks sold, what is the predicted value of the number of average daily COVID cases? Given an estimated coefficient _1 0.5 with a standard error (SE) of 0.2, test the null hypothesis that = 0 at the 5% level of significance. What is the alternative hypothesis? What is the t-statistic for the test? What is the critical t-value from Table B-1? What do you conclude