The manufacturer of Glo-More flat white interior latex paint claims one-coat coverage of 400 square feet per gallon on interior walls. A painter keeps careful track of 6 gallons and finds coverage (in square feet) of 360, 410, 380, 360, 390, 400. At α= 0.10 is there evidence that coverage is less than 400 square feet per gallon? Follow the steps for the critical value approach to test the claim. What is the critical value?