5) Consider a double-pane window consisting of two 4-mm-thick layer of glass (k=1Wm1K1) separated by a 10mm-wide stagnant air space. Room temperature =20 degree C. Outdoor temperature =10 degree C. Convection heat transfer coefficients on the inner and outer surfaces of the window are known: houtside=40Wm2K1, and hinside=10Wm2K1. The surface temperature of the glass on the outside is -7 degree C. Determine the thermal conductivity of the stagnant air. (3 pts)