In the laboratory, you are studying the first-order conversion of a reactant to products in a reaction vessel with a constant volume of . At 1:00 p.m., you start the reaction at 21 with 1.000 of . At 2:00 p.m., you find that 0.600 of remains, and you immediately increase the temperature of the reaction mixture to 31. At 3:00 p.m., you discover that 0.250 of is still present. You want to finish the reaction by 4:00 p.m. but need to continue it until only 0.040 of remains, so you decide to increase the temperature once again. What is the minimum temperature required to convert all but 0.040 of to products by 4:00 p.m.?