(Solved): Early Monday morning, the temperature in the lecture hall has fallen to 39F, the same as the te ...

Early Monday morning, the temperature in the lecture hall has fallen to $$39^{?}\mathrm{F}$$, the same as the temperature outside. At 7:00 A.M., the janitor turns on the furnace with the thermostat set at $$72^{?}\mathrm{F}$$. The time constant for the building is $$\frac{1}{\mathrm{K}}=3\mathrm{hr}$$ and that for the building along with its heating system is $$\frac{1}{{\mathrm{K}}_1}=\frac{2}{3}$$ $$\mathrm{hr}$$. Assuming that the outside temperature remains constant, what will be the temperature inside the lecture hall at 8:15 A.M.? When will the temperature inside the hall reach $$68^{?}\mathrm{F}$$ ? At 8:15 A.M., the temperature inside the lecture hall will be about $${}^{?}\mathrm{F}$$. (Round to the nearest tenth as needed.)