A building designer wishes to evaluate the R value of a 3.5 in-wide air gap in a wall for its insulatingeffect. The resistance to heat flow offered by convection is small, so he/she proposes lining the cavity's inner andouter surfaces with a highly reflecting aluminum foil film whose emissivity is 5%. Find the R value of this wall cavity,including both radiation and convection effects, if the temperatures of the walls facing the gap are 45oF and 55oF