Suppose a regression to explain district test scores obtains the following result: testser = 650 + 0.02 income + 0.22 expenditure - 12 str - 0.5 meal_pct - 0.2 calw_pct The following reports the F-stat for several hypothesis tests. For each, state the number of restrictions. Can you reject the null hypothesis at the 10% level? 5% level? Or 1% level? a. Null: The slope coefficients for income and expenditure are both zero. F = 4.4