$8-27$ A square room $3$ by $3$ m has a floor heated to $300$ K$,$ a ceiling at $290$ K$,$ and walls

that are assumed perfectly insulated. The height of the room is $2\mathrm{.}5$ m$.$ The emissivity

of all surfaces is $0\mathrm{.}8.$ Using the network method, find the net interchange between

floor and ceiling and the wall temperature.